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Biomedical subjects

J H Choi

Publications and source records attributed to J H Choi.

At least 145 records · Page 8Linked to original sources
PubMed2000

Fetal exposure to an intra-amniotic inflammation and the development of cerebral palsy at the age of three years.

OBJECTIVE: The aim of this study was to determine whether fetal exposure to intra-amniotic inflammation and a systemic fetal inflammatory response (funisitis) are associated with the development of cerebral palsy at the age of 3 years. STUDY DESIGN: This cohort study included 123 preterm singleton newborns (gestational age at birth, </=35 weeks) born to mothers who underwent amniocentesis and were followed up for >/=3 years. The presence of intra-amniotic inflammation was determined by elevated amniotic fluid concentrations of proinflammatory cytokines such as interleukins 6 and 8 and by amniotic fluid white blood cell count. Cytokine concentrations were measured with sensitive and specific immunoassays. Funisitis was diagnosed in the presence of neutrophil infiltration into the umbilical vessel walls or Wharton jelly. Cerebral palsy was diagnosed by neurologic examination at the age of 3 years. RESULTS: Newborns with subsequent development of cerebral palsy had a higher rate of funisitis and were born to mothers with higher median concentrations of interleukins 6 and 8 and higher white blood cell counts in the amniotic fluid compared with newborns without subsequent development of cerebral palsy (funisitis: 75% [9/12] vs 23% [24/105]; interleukin 6: median, 18.9 ng/mL; range, 0. 02-92.5 ng/mL; vs median, 1.0 ng/mL; range, 0.01-115.2 ng/mL; interleukin 8: median, 13.0 ng/mL; range, 0.1-294.5 ng/mL; vs median, 1.2 ng/mL; range, 0.05-285.0 ng/mL; white blood cell count: median, 198 cells/mm(3); range, 0->1000 cells/mm(3); vs median, 3 cells/mm(3); range, 0-19,764 cells/mm(3); P <.01 for each). After adjustment for the gestational age at birth, the presence of funisitis and elevated concentrations of interleukins 6 and 8 in amniotic fluid significantly increased the odds of development of cerebral palsy (funisitis: odds ratio, 5.5; 95% confidence interval, 1.2-24.5; interleukin 6: odds ratio, 6.4; 95% confidence interval, 1. 3-33.0; interleukin 8: odds ratio, 5.9; 95% confidence interval, 1. 1-30.7; P <.05 for each). CONCLUSION: Antenatal exposure to intra-amniotic inflammation and evidence of a systemic fetal inflammatory response (funisitis) are strong and independent risk factors for the subsequent development of cerebral palsy at the age of 3 years.

Amniotic Fluid↗
PubMed2000

PhyloDraw: a phylogenetic tree drawing system.

UNLABELLED: PhyloDraw is a unified viewing tool for phylogenetic trees. PhyloDraw supports various kinds of multi-alignment formats (Dialign2, Clustal-W, Phylip format, NEXUS, MEGA, and pairwise distance matrix) and visualizes various kinds of tree diagrams, e.g. rectangular cladogram, slanted cladogram, phylogram, unrooted tree, and radial tree. By using several control parameters, users can easily and interactively manipulate the shape of phylogenetic trees. This program can export the final tree layout to BMP (bitmap image format) and PostScript. AVAILABILITY: http://pearl.cs.pusan.ac.kr/phylodraw/ CONTACT: jhchoi@pearl.cs.pusan.ac.kr

Computational Biology↗
PubMed2000

Proteolytic cleavage of phospholipase C-gamma1 during apoptosis in Molt-4 cells.

Apoptosis is a cell suicide mechanism that requires the activation of cellular death proteases for its induction. We examined whether the progress of apoptosis involves cleavage of phospholipase C-gamma1 (PLC-gamma1), which plays a pivotal role in mitogenic signaling pathway. Pretreatment of T leukemic Molt-4 cells with PLC inhibitors such as U-73122 or ET-18-OCH(3) potentiated etoposide-induced apoptosis in these cells. PLC-gamma1 was fragmented when Molt-4 cells were treated with several apoptotic stimuli such as etoposide, ceramides, and tumor necrosis factor alpha. Cleavage of PLC-gamma1 was blocked by overexpression of Bcl-2 and by specific inhibitors of caspases such as Z-DEVD-CH(2)F and YVAD-cmk. Purified caspase-3 and caspase-7, group II caspases, cleaved PLC-gamma1 in vitro and generated a cleavage product of the same size as that observed in vivo, suggesting that PLC-gamma1 is cleaved by group II caspases in vivo. From point mutagenesis studies, Ala-Glu-Pro-Asp(770) was identified to be a cleavage site within PLC-gamma1. Epidermal growth factor receptor (EGFR) -induced tyrosine phosphorylation of PLC-gamma1 resulted in resistance to cleavage by caspase-3 in vitro. Furthermore, cleaved PLC-gamma1 could not be tyrosine-phosphorylated by EGFR in vitro. In addition, tyrosine-phosphorylated PLC-gamma1 was not significantly cleaved during etoposide-induced apoptosis in Molt-4 cells. This suggests that the growth factor-induced tyrosine phosphorylation may suppress apoptosis-induced fragmentation of PLC-gamma1. We provide evidence for the biochemical relationship between PLC-gamma1-mediated signal pathway and apoptotic signal pathway, indicating that the defect of PLC-gamma1-mediated signaling pathway can facilitate an apoptotic progression.

Amino Acid Sequence↗
PubMed2000

Platelet supernatant promotes proliferation of auricular chondrocytes and formation of chondrocyte mass.

Recently proposed procedures for in vitro generation of new cartilage may be difficult to perform in humans because so many chondrocytes are needed for tissue engineering. In this study the authors investigated new, efficient, low-cost techniques for the isolation and culture of chondrocytes from the ear cartilage of the rabbit. They performed a low-density monolayer culture with a low concentration (0.5%, 1%) of human platelet supernatant and observed cell proliferation (seeding efficiency, deoxyribonucleic acid synthesis), matrix synthesis (glycosaminoglycan synthesis), and the expression of type I and type II collagen (reverse transcriptase polymerase chain reaction). Seeding efficiency was increased in 1% of platelet supernatant-treated cultures by two to three times compared with untreated controls. One percent platelet supernatant had increased the incorporation of [3H]-thymidine by 1.9 to 2.5 times at 72 hours compared with controls. Glycosaminoglycan synthesis was increased in platelet supernatant-treated chondrocytes at 96 hours compared with controls. Chondrocytes treated with 1% platelet supernatant showed a decreased expression of the type II collagen gene. Supplementation with a high concentration (10%) of the platelet supernatant provided the conditions for in vitro chondrocyte mass formation. These results indicate that proliferation and matrix synthesis of auricular chondrocytes is stimulated by a low concentration of platelet supernatant. On the other hand, chondrocytes were immobilized by a high concentration of platelet supernatant. Platelet supernatant may be useful as an inexpensive autologous source of multiple growth factors to enhance chondrocyte proliferation, and also may play the role of scaffold for chondrocytes. Additional investigation is underway to generate culture conditions that promote the differentiation as well as the proliferation of chondrocytes.

Animals↗
PubMed2000

Keratosis lichenoides chronica: marked response to calcipotriol ointment.

Keratosis lichenoides chronica (KCL) is a rare dermatosis characterized by a distinctive seborrheic dermatitis-like facial eruption, together with violaceous, papular, and nodular lesions on the extremities and trunk, typically arranged in a linear and reticulate pattern. KLC is resistant to therapy, although spontaneous remission has been reported. We describe a 35-year-old woman with KLC who had the typical features of widespread violaceous, reticulate, and striae-like eruptions with a prominent keratotic component over a nine-year period and who responded well to treatment with calcipotriol ointment. The immunohistochemical profiles are presented in addition to typical histopathologic features.

Administration, Cutaneous↗
PubMed2000

Hyalinizing Spitz nevus.

A seventeen-year-old Korean girl had a reddish-brown papular lesion on the nose. Histopathologically, it proved to be a "hyalinizing Spitz nevus" with the characteristic features of a discohesive growth pattern of nevus cells and hyalinized stroma. Immunohistochemical stains showed positive reactivity of nevus cells with S-100 protein and Vimentin and negative stainings with HMB45, CD68, CEA and low molecular weight cytokeratin. Hyalinizing Spitz nevus may represent a variant in the spectrum of Spitz nevus.

Adolescent↗
PubMed2000

Carcinoma erysipelatoides originating from stomach adenocarcinoma.

Carcinoma erysipelatoides is an uncommon form of cutaneous metastasis, which is most commonly caused by breast carcinoma, it has rarely been linked to the primary cancers of other organs. We report a 36-year-old woman with carcinoma erysipelatoides originating from a gastric carcinoma. Immunohistochemical and morphologic studies of skin biopsies revealed that the signet ring cells in the dilated lymphatics originated from adenocarcinoma of the stomach.

Adenocarcinoma↗
PubMed2000

Overexpression of human telomerase RNA in Helicobacter pylori-infected human gastric mucosa.

Telomerase, an enzyme associated with cellular immortality and malignancy, plays an important role in cellular immortalization and tumorigenesis. Furthermore, overexpression of the RNA component of the telomerase, called human telomerase RNA (hTR), has been demonstrated in various human cancers as an early event. The pattern of hTR expression following Helicobacter pylori (H. pylori) infection in human gastric mucosa was investigated by a radioactive in situ hybridization (ISH) assay. Paraffin-embedded sections of 50 biopsy specimens taken from the gastric antrum of individual patients infected to different extents with H. pylori, as well as normal gastric mucosa, were studied. In normal gastric mucosa, only weak hTR expression was noted and the expression was limited to basal cells of the gastric glands. However, the degree of hTR expression gradually increased in parallel with the degree of H. pylori infection. The mean scores of gastric mucosa with mild, moderate and severe degrees of H. pylori infection were 2.3, 2.8, and 3.7 times higher than that of normal gastric mucosa, respectively. The results of this study suggested that up-regulation of hTR expression is a frequent and early event associated with H. pylori infection in the gastric mucosa and may play some role in gastric carcinogenesis. Sufficient synthesis of hTR during this early stage may be a prerequisite for telomerase reactivation to occur in gastric cancer.

Adult↗
PubMed2000

Hypereosinophilic syndrome presenting as cutaneous necrotizing eosinophilic vasculitis and Raynaud's phenomenon complicated by digital gangrene.

Cutaneous necrotizing eosinophilic vasculitis is a recently identified type of vasculitis that is characterized by an eosinophil-predominant necrotizing vasculitis affecting small dermal vessels. Clinically, it presents with pruritic erythematous and purpuric papules and plaques, peripheral eosinophilia and a good response to systemic steroid therapy. This vasculitis can be idiopathic or associated with connective tissue diseases. Although the pathogenic roles of eosinophil-derived granule proteins and interleukins have been documented in diseases associated with eosinophilia, a role of CD40 (a glycoprotein of the tumour necrosis factor receptor superfamily) has rarely been described. We describe two patients with idiopathic hypereosinophilic syndrome (HES) presenting with multiple erythematous patches and plaques on the lower extremities and Raynaud's phenomenon. They satisfied the criteria for the diagnosis of HES by clinical and laboratory investigations. Histopathology of the cutaneous lesions revealed prominent eosinophilic infiltration with local fibrinoid change in vessel walls in the dermis and subcutis. Immunohistochemical detection of CD3, CD4, CD8 and CD40 was performed. Infiltrating eosinophils were strongly stained by anti-CD40 monoclonal antibody. One patient improved with prednisolone, pentoxifylline and nifedipine, without recurrence. The other patient initially improved with steroids, but after self-withdrawal of steroid developed digital ischaemia that evolved to severe necrosis and required amputation. Cutaneous necrotizing eosinophilic vasculitis, Raynaud's phenomenon and digital gangrene may develop as cutaneous manifestations of HES. CD40 may play a part in the pathogenesis of eosinophilic vasculitis in HES.

Adult↗
PubMed2000

Phospholipase C is involved in kinetochore function in Saccharomyces cerevisiae.

The budding yeast PLC1 gene encodes a homolog of the delta isoform of mammalian phosphoinositide-specific phospholipase C. Here, we present evidence that Plc1p associates with the kinetochore complex CBF3. This association is mediated through interactions with two established kinetochore proteins, Ndc10p and Cep3p. We show by chromatin immunoprecipitation experiments that Plc1p resides at centromeric loci in vivo. Deletion of PLC1, as well as plc1 mutations which abrogate the interaction of Plc1p with the CBF3 complex, results in a higher frequency of minichromosome loss, nocodazole sensitivity, and mitotic delay. Overexpression of Ndc10p suppresses the nocodazole sensitivity of plc1 mutants, implying that the association of Plc1p with CBF3 is important for optimal kinetochore function. Chromatin extracts from plc1Delta cells exhibit reduced microtubule binding to minichromosomes. These results suggest that Plc1p associates with kinetochores and regulates some aspect of kinetochore function and demonstrate an intranuclear function of phospholipase C in eukaryotic cells.

Centromere↗
PubMed2000

The ethanol-soluble part of a hot-water extract from Artemisia iwayomogi inhibits liver fibrosis induced by carbon tetrachloride in rats.

This study was carried out to investigate the protective effects of the hot-water extract from Artemisia iwayomogi (Compositae) on carbon tetrachloride-induced liver fibrosis in rats. Liver injury was induced by oral administration of carbon tetrachloride (1 mL kg(-1)) twice a week during 4 weeks of A. iwayomogi treatment. Extracts from A. iwayomogi were prepared and administered to rats orally (2 g kg(-1) as A. iwayomogi for 4 weeks) as follows: group 1, hot-water extract; group 2, ethanol-soluble part of hot-water extract; group 3, ethanol-insoluble part of hot-water extract; and group 4, methanol extract. In rats treated with the ethanol-soluble part of the hot-water extract, liver hydroxyproline content was reduced to 74% that of carbon tetrachloride control rats (P < 0.05). Protein expression of alpha smooth muscle cell like actin was also decreased in rats treated with the ethanol-soluble part of the hot-water extract, which indicates inhibition of hepatic stellate cell activation. Liver malondialdehyde levels were significantly lowered in rats treated with the ethanol-soluble part of hot-water extract (P < 0.05). Serum cholesterol levels in rats treated with hot-water extract, ethanol-soluble or -insoluble parts of hot-water extract or methanol extract were significantly reduced when compared with those of carbon tetrachloride control rats (P < 0.05). The ethanol-soluble part of the hot-water extract from A. iwayomogi inhibited fibrosis and lipid peroxidation in rats with liver fibrosis induced by carbon tetrachloride. Both hot-water extract (either ethanol-soluble or -insoluble) and methanol extract of A. iwayomogi also lowered serum cholesterol levels in fibrotic rats.

Animals↗
PubMed2000

A case of primary intestinal T-cell lymphoma involving entire gastrointestinal tract: esophagus to rectum.

Primary intestinal T-cell lymphoma is a rare disease entity, which is approximately 10% to 25% of intestinal lymphomas, and most of the lymphomas occur in the small intestine. We report here a case of a 56-year-old woman who has been suffering from chronic diarrhea and weight loss for 6 months. Abdominal CT scan and small bowel series showed diffuse wall thickening of the small bowel. Gastroscopic examination showed diffuse erythematous lesions on the esophagus and small gastric ulcerations on the antrum of the stomach, and colonoscopic examination also showed multiple punched-out ulcerations and erosions on the entire colon, including the sigmoid colon to the terminal ileum. Diffuse infiltration of CD 3 positive lymphoma cells was found on biopsy. The patient was diagnosed as primary intestinal T-cell lymphoma with diffuse involvement of the entire gastrointestinal tracts from the esophagus to the rectum. Although the patient received systemic combination chemotherapy and achieved partial response initially, the lymphoma relapsed repeatedly.

Esophageal Neoplasms↗
PubMed2000

Increased expression of cyclooxygenase-2 protein in human gastric carcinoma.

Gastric adenocarcinoma is one of the most common malignancies in the world, and yet little is known about its molecular process of development and progression. Recent studies have suggested that ingestion of nonsteroid anti-inflammatory drugs reduces the risk of colon cancer, presumably by inhibiting the cyclooxygenase (COX) enzyme. COX-2, one isoform of the COX enzyme, is the rate-limiting enzyme in prostaglandin synthesis, and the function of this enzyme is thought to relate to inflammatory processes and carcinogenesis. To understand the role of COX enzyme in gastric cancer, we measured COX-2 expression in 104 human gastric carcinoma tissues by immunohistochemical analysis. We obtained tissue specimens from 104 surgically resected gastric adenocarcinoma patients. We performed immunohistochemical stain for human COX-2 with polyclonal antibody in gastric carcinoma. After curative resection and extensive lymph node dissection, all patients received adjuvant chemotherapy containing 5-fluorouracil. Expression of COX-2 showed cytoplasmic staining, not only in cancer cells but also in precancerous lesions such as metaplastic and adenomatous cells. We confirmed up-regulation of COX-2 in gastric cancer tissues compared with normal paired mucosa using Western blot analysis. There was no correlation between clinicopathological characteristics of gastric cancer patients and intensity of COX-2 protein expression. This study indicates that COX-2 protein over-expression may contribute to an early event of gastric cancer development, and it further suggests that selective inhibition of COX-2 may provide a chemopreventive effect against gastric carcinogenesis.

Adenocarcinoma↗
PubMed2000

Lutein and zeaxanthin concentrations in rod outer segment membranes from perifoveal and peripheral human retina.

PURPOSE: In addition to acting as an optical filter, macular (carotenoid) pigment has been hypothesized to function as an antioxidant in the human retina by inhibiting the peroxidation of long-chain polyunsaturated fatty acids. However, at its location of highest density in the inner (prereceptoral) layers of the foveal retina, a specific requirement for antioxidant protection would not be predicted. The purpose of this study was to determine whether lutein and zeaxanthin, the major carotenoids comprising the macular pigment, are present in rod outer segment (ROS) membranes where the concentration of long-chain polyunsaturated fatty acids, and susceptibility to oxidation, is highest. METHODS: Retinas from human donor eyes were dissected to obtain two regions: an annular ring of 1.5- to 4-mm eccentricity representing the area centralis excluding the fovea (perifoveal retina) and the remaining retina outside this region (peripheral retina). ROS and residual (ROS-depleted) retinal membranes were isolated from these regions by differential centrifugation and their purity checked by polyacrylamide gel electrophoresis and fatty acid analysis. Lutein and zeaxanthin were analyzed by high-performance liquid chromatography and their concentrations expressed relative to membrane protein. Preparation of membranes and analysis of carotenoids were performed in parallel on bovine retinas for comparison to a nonprimate species. Carotenoid concentrations were also determined for retinal pigment epithelium harvested from human eyes. RESULTS: ROS membranes prepared from perifoveal and peripheral regions of human retina were found to be of high purity as indicated by the presence of a dense opsin band on protein gels. Fatty acid analysis of human ROS membranes showed a characteristic enrichment of docosahexaenoic acid relative to residual membranes. Membranes prepared from bovine retinas had protein profiles and fatty acid composition similar to those from human retinas. Carotenoid analysis showed that lutein and zeaxanthin were present in ROS and residual human retinal membranes. The combined concentration of lutein plus zeaxanthin was 70% higher in human ROS than in residual membranes. Lutein plus zeaxanthin in human ROS membranes was 2.7 times more concentrated in the perifoveal than the peripheral retinal region. Lutein and zeaxanthin were consistently detected in human retinal pigment epithelium at relatively low concentrations. CONCLUSIONS: The presence of lutein and zeaxanthin in human ROS membranes raises the possibility that they function as antioxidants in this cell compartment. The finding of a higher concentration of these carotenoids in ROS of the perifoveal retina lends support to their proposed protective role in age-related macular degeneration.

Aged↗
PubMed2000

Effects of age and dietary restriction on lifespan and oxidative stress of SAMP8 mice with learning and memory impairments.

This study was to evaluate the effect of dietary restriction (DR) on lifespan and oxidative stress of dementia mouse model SAMP8 with impaired learning and memory. SAMP8 female mice were fed either ad libitum (AL) or fed 60% of food intake of AL. Results showed that basal metabolic rates (BMR) were significantly lower (15 to 22%) in DR with increased median and maximum lifespans, suggesting feed and gross efficiencies were significantly lower in DR than in AL. Grading score of senescence resulted in a marked improvement about 2-fold by DR compared with AL. The amounts of lipofuscin at 12 months were significantly lowered 16% in DR than that of AL. Median and maximal lifespans significantly increased (28.5% and 16.4%, respectively) by DR, and also lowered superoxide radical about 15 approximately 45% in DR compared with AL at 4, 8 and 12 months of age. On the other hand, superoxide dismutase (SOD) activities were higher (about 15 approximately 30%) in DR than those in AL group of SAMP8 except for 4 months of age. Our results suggest that 40% calorie restricted SAMP8 can effectively suppress dementia-related abnormalities during aging.

Aging↗