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Biomedical subjects

K H Cho

Publications and source records attributed to K H Cho.

At least 19 recordsLinked to original sources
PubMed2003

Cutaneous metastasis to the scalp from squamous cell carcinoma of the cervix.

Carcinoma of the cervix is a common neoplasm. Early detection and improved treatment techniques have resulted in better control of cancer and longer survival, however, invasive and metastatic disease still occur. Cervical cancer usually spreads through direct local extension and via the lymphatics, haematogenous metastasis is relatively infrequent and cutaneous metastases are very rare. Metastasis to the scalp is extremely rare and only three cases of scalp metastasis from cervical cancer have been reported in the literature. We now report a patient with cervical cancer who presented with metastasis to this very unusual site.

Carcinoma, Squamous Cell↗
PubMed2003

A fatal case of Vibrio vulnificus meningoencephalitis.

The objective of this paper is to report a rare case of Vibrio vulnificus presenting as meningoencephalitis without a wound infection. Vibrio vulnificus is capable of causing severe and often fatal infections in susceptible individuals. It commonly causes necrotizing wound infections, primary septicemia, and gastroenteritis. A 69-year-old man had meningoencephalitis with lesion on the red nucleus, substantia nigra, basal ganglia, and dentate nucleus as the initial clinical manifestation of a V. vulnificus infection. This is the first case of V. vulnificus infection in which MRI demonstrated the involvement of deep nuclei of the brain.

Aged↗
PubMed2002

Imaging features of ischial bursitis with an emphasis on ultrasonography.

OBJECTIVE: The aim of this study was to evaluate the imaging features of ischial bursitis with an emphasis on ultrasonography (US). DESIGN AND PATIENTS: Our study included 31 patients with a painful mass or tenderness in their buttock who underwent US (n=27), CT (n=1), or MR imaging (n=4). A needle aspiration (n=6) or a bursal excision (n=5) was performed in those patients who had no clinical improvement in spite of the conservative treatment. Evaluation included lesion location, size, wall of the bursae, and intrinsic characteristics on US, CT and MR imaging. RESULTS: Ischial bursitis was superficial to the ischial tuberosity in all patients (n=31). The lesion ranged from 1.5 cm to 7 cm (average 3.8 cm) in diameter. The bursal wall was identifiable in 25 cases (81%). Internal septa and mural nodules were seen in 12 (39%) and 17 cases (55%), respectively. Sonography showed that fluid within the bursa was hypoechoic (59%), hyperechoic (26%), or of mixed echogenicity (15%). The bursae were compressible by the transducer. Power Doppler examination (n=7) showed hypervascularity of the bursal wall. All lesions imaged with contrast-enhanced CT and MR imaging had an enhancing thin wall and mural nodule. CONCLUSIONS: Ischial bursitis, superficial to the ischial tuberosity, can be clearly demonstrated on sonography and appears as a thin-walled cystic lesion, with or without internal septa and mural nodules.

Adult↗
PubMed2002

Acute effects of UVB radiation on the proliferation and differentiation of keratinocytes.

PURPOSE: The effects of UVB radiation on the proliferation and differentiation of epidermal keratinocytes were investigated with respect to timing, dosage, and repeated exposures. METHODS: Nine healthy volunteers were placed into three subgroups and exposed to UVB radiation on buttock skin using a Waldmann UV 800 unit fitted with Philips TL-20W/12 fluorescent lamps. Three volunteers were given 2 MED of UVB and biopsied at: pre-exposure, 24, 48 and 72 h after UVB exposure. For three volunteers, 1 MED, 2 MED, 3 MED of UVB were applied. After 48 h, biopsies were taken from non-irradiated and irradiated sites. Finally, three volunteers received 1 MED of UVB daily for 5 days, and the non-irradiated and irradiated sites were biopsied 48 h after the final exposure. The expression of proliferation and differentiation markers by keratinocytes were detected by immunohistochemical staining, and the results were analysed quantitatively by image analysis. RESULTS: The expression of proliferation and differentiation markers was observed prominently 48 h after irradiation. Higher doses of UVB caused an increase in proliferation and differentiation marker expression. Repeated exposures potentiated the effect of UVB radiation. CONCLUSION: UVB irradiation concomitantly promotes epidermal proliferation and differentiation. Responses were maximal 48 h after irradiation. This effect of UVB increases linearly according to dose and repetition.

Adult↗
PubMed2001

Cytological observation of two environmental genic male-sterile lines of rice.

We report here two environmental genic male-sterilities (EGMS) in rice. These two EGMS rice lines, thermo-sensitive genic male-sterility (TGMS) and photoperiod-sensitive genic male-sterility (PGMS), are controlled by temperature and photoperiod, respectively, in determining their male-sterility. Male-sterility of the TGMS and PGMS was found to be induced when they were grown at 32 degrees C/26 degrees C (day/night) with 14 h daylight, while they were fertile at 26 degrees C/20 degrees C (day/night) with 10 h daylight in a growth chamber. We also examined their anther structures under a light microscope. The light microscopic observation revealed that the EGMS lines showed a complete pollen abortion at the sterile growth condition while they produced normal fertile pollens at the fertile growth condition.

Fertility↗
PubMed2001

Inhibition of microsomal ATPases by high concentration of Mg2+ in tracheal epithelial cells.

Previous work in our laboratory established the presence of two types of microsomal ATPases, a low-affinity vanadate-sensitive (LAVS) and a high-affinity vanadate-sensitive (HAVS) ATPases, in tracheal epithelial cells. These ATPases were identified as Ca2+-ATPases by specific inhibitors and microsomal Ca2+ uptakes. Since the regulatory roles of Mg2+ on both cellular Ca2+-signaling and epithelial transports were demonstrated, the effects of Mg2+ on these ATPases were investigated. Mg2+-dependence of ATPase activity appeared bell-shaped with a maximal activity at 1-2 mM Mg2+ and Mg2+ at higher than 2 mM inhibited these enzymes. In a kinetic analysis of the LAVS ATPase inhibition, high concentration of Mg2+ appeared to inhibit the binding of ATP to a substrate-binding site. The microsomal 45Ca2+ uptakes mediated by both ATPases were also inhibited by high concentration of Mg2+. In order to test whether high concentration of Mg2+ directly inhibits these enzymes, microsomes were made leaky by the treatment of Triton X-100 and the microsomal ATPases were solubilized with CHAPS. The leaky microsomal ATPases and CHAPS-solubilized ATPases were similarly inhibited by high concentration of Mg2+, suggesting that Mg2+ directly inhibit these enzymes. In conclusion, Mg2+ has two types of modulatory effects on these enzymes, a catalytic effect at low concentration and an inhibitory effect at high concentration.

Adenosine Triphosphatases↗
PubMed2001

Effects of collagen IV and laminin on the reconstruction of human oral mucosa.

To investigate the effects of basement membrane proteins on the reconstruction of mucosa equivalent, oral mucosa substitute were cultured on (1) type I collagen gels, (2) type IV collagen-coated type I collagen gels, (3) laminin-coated type I collagen gels, and (4) type I collagen gels containing both type IV collagen and laminin. H/E and PAS staining showed that the characteristics of the oral mucosa were preserved under all the experimental conditions. However, the basal keratinocytes appeared cuboidal when the type I collagen gels were coated with type IV collagen plus laminin. The expression of the differentiation markers was similar, but weak staining of filaggrin, K13, and involucrin was observed with the type IV collagen plus laminin coating. Furthermore, electron microscopy revealed that the size of the basal keratinocytes was relatively small and uniform when both type IV collagen and laminin were used. These findings suggested that these two major basement membrane proteins are important in the process of differentiation in mucosal keratinocytes.

Animals↗
PubMed2001

Does the extent of surgery have an impact on the survival of patients who receive postoperative radiation therapy for supratentorial low-grade gliomas?

We evaluate the impact of extent of surgery (EOS) on survival of patients with supratentorial nonpilocytic low-grade gliomas (LGG) treated with postoperative radiation therapy (PORT). Sixty-five patients with pathologically confirmed supratentorial nonpilocytic LGG (36 astrocytomas and 29 oligodendrogliomas) were treated with PORT after different extents of surgery: 12 gross total resections (GTR), 27 minimal or subtotal resections (MR/SR), and 26 biopsies (B). EOS was confirmed with postoperative imaging. The median radiation dose delivered was 5,940 cGy (range, 4,950-6,620 cGy). One of 12 patients (8%) in the GTR group and 12 of 53 patients (23%) in the less than GTR group demonstrated contrast enhancement. The median follow-up was 61 months (range 5-194 month). The 10-year overall survival (OS) was 82.5% and 32% for the GTR and the less than GTR groups, respectively (P = 0.0008). The corresponding 10-year disease-specific survival (DSS) was 90% and 41.4%%, respectively (P = 0.001). Multivariate analysis showed that only contrast enhancement and EOS were predictors for OS and DSS. Our data suggest that EOS correlates with OS and DSS in patients who have PORT. GTR should be the goal if technically achievable without causing significant morbidity, and its combination with PORT is compatible with long-term survival.

Adult↗
PubMed2001

Digitizing pediatric chest radiographs: comparison of low-cost, commercial off-the-shelf technologies.

OBJECTIVE: To compare low-cost, off-the-shelf technology for digitizing pediatric chest radiographs. MATERIALS AND METHODS: Forty pediatric chest radiographs (hard copy), each with a single abnormality, were digitized using a commercial film digitizer and two low-cost METHODS: a digital camera and a flatbed scanner. A stratified, randomized, block design was used where 20 readers evaluated 40 different images to determine the ability to accurately detect the abnormality. Readers then rated all 160 images (40 images x 4 methods) for conspicuity of the abnormality and overall image quality. RESULTS: Abnormalities were correctly identified on 82.3 % of hard copy images, 82.9 % of flatbed scanner images, 74.3 % of film digitizer images, and 69.7 % of digital camera images (p < 0.05) when compared to hard copy or flatbed scanner images. Lesion conspicuity was rated higher on hard copy (p < 0.05) than all digitized images. Conspicuity ratings were similar for flatbed scanner and film digitizer images, but lower in digital camera images (p < 0.05). For overall image quality, all were rated significantly different from each other (p < 0.05), with hard copy > flatbed scanner > film digitizer > digital camera images. CONCLUSION: A low-cost flatbed scanner yielded digital pediatric chest images which were significantly superior to digital camera images While flatbed scanner images were interpreted with the equivalent diagnostic accuracy of hard copy images, they were rated lower for image quality and lesion conspicuity.

Adolescent↗
PubMed2001

Fibrosarcoma in bizarre parosteal osteochondromatous proliferation.

Bizarre parosteal osteochondromatous proliferation (BPOP) is a rare benign lesion predominantly involving the small bones of the hands and feet. Malignant transformation in BPOP has not been documented in the English literature. This report presents the coexistence of fibrosarcoma with BPOP in the right distal fibula of an 18-year-old woman.

Adolescent↗
PubMed2001

Pathological findings in cumulative irritation induced by SLS and croton oil in hairless mice.

It is known that the pathological features of acute irritant contact dermatitis are specific according to the irritant. However, in chronic irritant contact dermatitis, it is not clear whether specific patterns exist. To investigate whether the specific pathology of acute irritant contact dermatitis is sustained in chronic irritant contact dermatitis, sodium lauryl sulfate (SLS) and croton oil were applied 3x a week for 2 weeks on the dorsal skin of hairless mice using Finn Chambers. The pathologic changes induced by irritants at various concentrations were evaluated using H&E and Luna's staining, as well as immunohistochemistry for 5-bromo-2-deoxyuridine (BrdU), keratin 6 and loricrin. Our results showed that epidermal hyperplasia and inflammatory infiltration were relatively marked in the groups treated with higher concentrations of irritants. These features were more prominent in the 1% croton oil treated group than in the 0.25% SLS treated group. However, lower concentrations of irritants resulted in very similar histological changes, characterized by epidermal hyperplasia with minimal inflammatory infiltration, irrespective of the chemical. Our results suggest that the histological responses to irritants vary with concentration in cumulative irritation, as in acute irritation, but repetitive mild irritation may evoke common histological changes, characterized by epidermal hyperplasia with minimal inflammatory infiltration, irrespective of the chemical used.

Animals↗
PubMed2001

Ceramide inhibits cell proliferation through Akt/PKB inactivation and decreases melanin synthesis in Mel-Ab cells.

Ceramide is a bioactive sphingolipid that mediates a variety of cell functions. However, the effects of ceramide on cell growth and the melanogenesis of melanocytes are not known. In the present study, we investigated the actions of cell-permeable ceramide and its possible role in the signaling pathway of a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Our results show that C2-ceramide inhibits DNA synthesis in Mel-Ab cells and G361 human melanoma cells in a dose-dependent manner. Cell cycle analysis confirmed the inhibition of DNA synthesis by a reduction in the S phase. To investigate the ceramide signaling pathway, we studied whether C2-ceramide is able to influence extracellular signal-regulated kinase (ERK) and/or Akt/protein kinase B (PKB) activation. We demonstrated that phosphorylated Akt/PKB is decreased by C2-ceramide, whereas phosphorylated ERK was only slightly affected. Therefore, the C2-ceramide-induced inactivation of Akt/PKB may be closely related to the reduced cell proliferation of Mel-Ab cells. Furthermore, we assessed the effects of C2-ceramide on the pigmentation of Mel-Ab cells. The results obtained showed that the melanin content of cells was significantly reduced by C2-ceramide at concentrations in the range of 1-10 microM, and that the pigmentation-inhibiting effect of C2-ceramide is much greater than that of kojic acid at 1-100 microM. In addition, we found that the activity of tyrosinase is reduced by C2-ceramide treatment. Our results demonstrate that C2-ceramide reduces the pigmentation of Mel-Ab cells by inhibiting tyrosinase activity.

Animals↗
PubMed2001

Single dose radiation is more effective for the UV-induced activation and proliferation of melanocytes than fractionated dose radiation.

PURPOSE: To establish whether the effect of fractionating radiation modifies the effects of ultraviolet (UV) radiation on epidermal melanocytes, we compared the clinical and histological effects of single high dose radiation against repeated intermediate to low dose radiation on epidermal melanocytes. METHODS: Three minimal erythema UV doses (MED) were administered to three sites on the buttocks of healthy volunteers. One site was irradiated with 0.5 MED UV every day for 6 consecutive days, another site was irradiated with 1 MED UV every second day, and a third site received a single dose of radiation with 3 MED UV. The treatment was replicated on the other buttock. For the evaluation of UV-induced erythema and pigmentation, erythema and melanin indices were measured at 2 and 14 days post-irradiation. For purposes of histological evaluation, tissue specimens taken from each irradiated site at 2 and 14 days post-irradiation and were stained with monoclonal antibodies against Mel-5, HMB-45 and tyrosinase. Fontana-Masson silver staining, DOPA staining and split DOPA reactions were also performed. RESULTS: At 14 days post-irradiation, UV radiation induced melanocyte activation, proliferation and melanogenesis in proportion to the radiation dose administered to each fraction. The most prominent responses were observed after single high doses of radiation. CONCLUSION: When the total administered dose is identical, fractionation of radiation dose diminishes the effects of UV radiation on epidermal melanocytes. Furthermore, long, uninterrupted doses of UV radiation were found to more effective in inducing melanogenesis and melanocyte activation.

Adult↗
PubMed2001

Aging- and photoaging-dependent changes of enzymic and nonenzymic antioxidants in the epidermis and dermis of human skin in vivo.

This is a comprehensive study of the changes in major antioxidant enzymes and antioxidant molecules during intrinsic aging and photoaging processes in the epidermis and dermis of human skin in vivo. We show that the activities of superoxide dismutase and glutathione peroxidase are not changed during these processes in human skin in vivo. Interestingly, the activity of catalase was significantly increased in the epidermis of photoaged (163%) and naturally aged (118%) skin (n = 9), but it was significantly lower in the dermis of photoaged (67% of the young skin level) and naturally aged (55%) skin compared with young (n = 7) skin. The activity of glutathione reductase was significantly higher (121%) in naturally aged epidermis. The concentration of alpha-tocopherol was significantly lower in the epidermis of photoaged (56% of young skin level) and aged (61%) skin, but this was not found to be the case in the dermis. Ascorbic acid levels were lower in both epidermis (69% and 61%) and dermis (63% and 70%) of photoaged and naturally aged skin, respectively. Gluta thione concentrations were also lower. Uric acid did not show any significant changes. Our results suggest that the components of the antioxidant defense system in human skin are probably regulated in a complex manner during the intrinsic aging and photoaging processes.

Adult↗
PubMed2001

Modulation of skin collagen metabolism in aged and photoaged human skin in vivo.

To the best of our knowledge, no study has been conducted to date to directly compare the collagen metabolism of photoaged and naturally aged human skin. In this study, we compared collagen synthesis, matrix metalloproteinase-1 levels, and gelatinase activity of sun-exposed and sun-protected skin of both young and old subjects. Using northern blot analysis, immunohistochemical stain, and Western blot analysis, we demonstrated that the levels of procollagen type I mRNA and protein in photoaged and naturally aged human skin in vivo are significantly lower than those of young skin. Furthermore, we demonstrated, by northern blot analysis, that the procollagen alpha1(I) mRNA expression of photoaged skin is much greater than that of sun-protected skin in the same individual. In situ hybridization and immunohistochemical stain were used to show that the expression of type I procollagen mRNA and protein in the fibroblasts of photoaged skin is greater than for naturally aged skin. In addition, it was found, by Western blot analysis using protein extracted from the dermal tissues, that the level of procollagen type I protein in photoaged skin is lower than that of naturally aged skin. The level of matrix metalloproteinase-1 protein and the activity of matrix metalloproteinase-2 were higher in the dermis of photoaged skin than in naturally aged skin. Our results suggest that the natural aging process decreases collagen synthesis and increases the expression of matrix metalloproteinases, whereas photoaging results in an increase of collagen synthesis and greater matrix metalloproteinase expression in human skin in vivo. Thus, the balance between collagen synthesis and degradation leading to collagen deficiency is different in photoaged and naturally aged skin.

Adult↗
PubMed2001

Organization and developmental expression of the mosquito vitellogenin receptor gene.

Vitellogenin is a precursor of the major yolk protein, vitellin. It is internalized by developing oocytes via receptor-mediated endocytosis. Previously, we characterized the vitellogenin receptor (VgR) from oocytes of the mosquito Aedes aegypti [Sappington, T.W., Kokoza,V.A., Cho,W.L. and Raikhel,A.S. (1996) Molecular characterization of the mosquito vitellogenin receptor reveals unexpected high homology to the Drosophila yolk protein receptor. Proc Natl Acad Sci USA 93: 8934-8939]. The VgR receptor has a unique structure with two putative ligand-binding domains. In order to understand the regulation of this important molecule, we characterized the VgR gene structure and its expression during vitellogenesis in the mosquito A. aegypti. We report here that the VgR gene was separated by five introns that have an average length of 60 bp, except for the second intron which was more than 20 kb long. Most introns were located within the coding regions of the first protein domain. We isolated two allelic variations of the VgR gene, VgR1 and VgR2, the nucleotide sequences of which differing only in their 5'-flanking regions. Considering their frequency in the mosquito genome, VgR2 appeared to be a major allele. The expression of VgR mRNA was studied by the Northern blot analysis and in situ hybridization. The level of the VgR transcript started to rise in the ovary one day post-eclosion. It continued its dramatic rise during the vitellogenic period, reaching its peak at 24 h PBM. The VgR transcript was present exclusively in ovaries where it was seen in oocytes and nurse cells of primary follicles and germ-line cells of the germarium.

Aedes↗