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Biomedical subjects

J W Choi

Publications and source records attributed to J W Choi.

At least 37 records · Page 2Linked to original sources
PubMed2002

Tissue plasminogen activator levels change with plasma fibrinogen concentrations during pregnancy.

To investigate the relationship between coagulation activities and the fibrinolytic system during normal pregnancy, we measured the plasma concentrations of coagulation factors, antithrombin III (AT III), D-dimer, tissue plasminogen activator (tPA), total protein S (TPS), and plasminogen activator inhibitor type 1 (PAI-1) in 436 apparently healthy pregnant, postpartum, and nonpregnant women. There were no significant changes in AT III, TPS, and factor XI concentrations during pregnancy and puerperium. However, factor VII, VIII, IX, and XII activities increased gradually as pregnancy progressed, reached maximum values in the third trimester, and returned to nonpregnant levels by 5-8 weeks postpartum. Plasma D-dimer levels in the third trimester of pregnancy were 1.23+/-0.42 micro g/ml, significantly higher than for the first trimester (0.34+/-0.16 micro g/ml, P<0.01). The tPA antigen levels averaged 1.8-fold higher in the late third trimester than in the first trimester; the plasma fibrinogen concentrations averaged 1.6-fold higher in the late third trimester than in the first trimester. Compared to the peak values during pregnancy, tPA levels averaged 39.8% lower and plasma fibrinogen concentrations averaged 40.0% lower at 5-8 weeks postpartum. The tPA levels correlated strongly with the plasma fibrinogen concentrations ( r=0.52, P<0.01). In short, this study shows that tPA levels change in parallel with plasma fibrinogen concentrations during and after normal pregnancy.

Adult↗
PubMed2002

Significance of fetal hemoglobin-containing erythroblasts (F blasts) and the F blast/F cell ratio in myelodysplastic syndromes.

To investigate the relationship between the fetal hemoglobin-containing erythroblasts (F blasts) and apoptosis in myelodysplastic syndromes (MDS), we immunohistochemically assessed F blasts, F cells, and apoptosis in 137 patients with MDS. A marked increase in the number of F blasts in the bone marrow was identified in 116 of 137 patients (84.7%), and the number of F cells was elevated in 54 patients (39.4%). Among the erythroblasts stained by anti-glycophorin C antibody, the mean percentage of F blasts was 14.63 +/- 9.17% in MDS, which was significantly higher than that in non-MDS patients with stress erythropoiesis (4.82 +/- 3.35%, P < 0.01), although there were no significant differences in the number of F cells between these groups. In particular, 62 of the 137 MDS patients (45.3%) had an apparent increase in F blasts but no elevation of F cells. The apoptotic rate was significantly higher in the patients with a F blast/F cell (Fb/Fc) ratio >or=5.0 than in those with a Fb/Fc ratio <1.0 (P < 0.01). The results indicate that F cell precursors are incapable of maturing into functioning end-stage F cells, presumably owing to apoptotic cell death. The measurement of F blasts in the bone marrow is needed for the precise evaluation of fetal-type erythropoiesis in MDS.

Adult↗
PubMed2002

Production of red pigment by submerged culture of Paecilomyces sinclairii.

AIMS: From a survey of submerged culture of edible mushrooms, a high pigment-producing fungus Paecilomyces sinclairii was selected and its optimal culture conditions investigated. METHODS AND RESULTS: The optimal culture conditions for pigment production were as follows: inoculum age, 3 d; temperature, 25 degrees C; initial pH, 6.0; carbon source, 1.5% (w/v) soluble starch; nitrogen source, 1.5% (w/v) meat peptone. Although addition of 10 mmol l(-1) CaCl2 to the culture medium slightly increased pigment production, most of the bio-elements examined had no notable or detrimental effect on pigment production. CONCLUSIONS: Under the optimal conditions obtained in the flask culture tested, a ninefold increase in pigment production (4.4 g l(-1)) was achieved using a 5(-l) batch fermenter. Paecilomyces sinclairii secreted water-soluble red pigment into the culture medium. The pigment colour was strongly dependent on the pH of the solution: red at pH 3-4, violet at pH 5-9 and pink at pH 10-12. SIGNIFICANCE AND IMPACT OF THE STUDY: The high concentration of pigment (4.4 g l(-1)) produced by P. sinclairii demonstrates the possibility of commercial production of pigment by this strain, considering its relatively high production yield and light stability.

Bioreactors↗
PubMed2002

Physical map of the chromosome 6q22 region containing the oculodentodigital dysplasia locus: analysis of thirteen candidate genes and identification of novel ESTs and DNA polymorphisms.

Oculodentodigital dysplasia (ODDD) is an autosomal dominant condition with congenital anomalies of the craniofacial and limb regions and neurodegeneration. Genetic anticipation for the dysmorphic and neurologic features has been inferred in a few families. Our previous linkage studies have refined the ODDD candidate region to chromosome 6q22-->q23. In an attempt to clone the ODDD gene, we created a yeast artificial chromosome contig with 31 redundant clones spanning the region and identified and ordered candidate genes and markers. Fluorescent IN SITU hybridization mapped two of these YAC clones to chromosome 6q22.2 telomeric to a known 6q21 fragile site, excluding it as a possible cause of the suggested anticipation. We performed mutation analysis on thirteen candidate genes - GRIK2, HDAC2, COL10A1, PTD013, KPNA5, PIST, ROS1, BRD7, PLN, HSF2, PKIB, FABP7, and HEY2. Although no mutations were found, we identified 44 polymorphisms, including 28 single nucleotide polymorphisms. Direct cDNA selection was performed and fifty-five clones were found to contain sequences that were not previously reported as known genes or ESTs. These clones and polymorphisms will assist in the further characterization of this region and identification of disease genes.

Abnormalities, Multiple↗
PubMed2001

Glucocorticoids exacerbate peroxynitrite mediated potentiation of glucose deprivation-induced death of rat primary astrocytes.

Glucocorticoids have been implicated in the exacerbation of several types of neurotoxicity in various neuropathological situations. In this study, we investigated the effect of a glucocorticoid dexamethasone on glucose deprivation induced cell death of immunostimulated rat primary astrocytes, which is dependent on the production of peroxynitrite from the immunostimulated cells [Choi et al. Glia, 31(2001) 155-164; J. Neuroimmunol. 112 (2001) 55-62]. Glucose deprivation in immunostimulated rat primary astrocytes results in the release of lactate dehydrogenase (LDH) after 5 h and co-treatment with dexamethasone (1-1000 nM) dose-dependently increased LDH release. Treatment of the exogenous peroxynitrite generator SIN-1 (20 microM), plus glucose deprivation, also increased LDH release after 6 h and co-treatment with dexamethasone dose-dependently increased LDH release. A glucocorticoid receptor antagonist, RU-486, reversed the potentiation of cell death by dexamethasone. Glucose deprivation in immunostimulated cells decreased the intracellular ATP levels, which preceded LDH release from the cell, and co-treatment with dexamethasone dose-dependently potentiated the depletion of intracellular ATP levels. In addition, dexamethasone further deteriorated SIN-1 plus glucose deprivation-induced decrease in mitochondrial transmembrane potential in rat primary astrocytes, which was reversed by RU-486. The results from the present study suggest that glucocorticoids may be detrimental to astrocytes in situations where activation of glial cells are observed, including ischemia and Alzheimer's disease, by mechanisms involving depletion of intracellular ATP levels and deterioration of mitochondrial transmembrane potentials.

Adenosine Triphosphate↗
PubMed2001

Dehydroepiandrosterone inhibits the death of immunostimulated rat C6 glioma cells deprived of glucose.

Pretreatment of interferon-gamma and lipopolysaccharides made C6 glioma cells highly vulnerable to glucose deprivation. Neither 12 h of glucose deprivation nor 2-day treatment with interferon-gamma (100 U/ml) and lipopolysaccharides (1 microg/ml) altered the viability of C6 glioma cells. However, significant death of immunostimulated C6 glioma cells was observed after 5 h of glucose deprivation. The augmented death was prevented by dehydroepiandrosterone (DHEA) treatment during immunostimulation, but not by DHEA treatment during glucose deprivation. DHEA reduced the rise in nitrotyrosine immunoreactivity, a marker of peroxynitrite, and superoxide production in glucose-deprived immunostimulated C6 glioma cells. DHEA, however, did not protect glucose-deprived C6 glioma cells from the exogenously produced peroxynitrite by 3-morpholinosydnonimine. Further, DHEA did not alter the production of total reactive oxygen species and nitric oxide in immunostimulated C6 glioma cells. Superoxide dismutase (SOD) and the synthetic SOD mimetic Mn(III)tetrakis (4-benzoic acid) porphyrin inhibited the death of glucose-deprived immunostimulated C6 glioma cells. In addition, a superoxide anion generator paraquat reversed the protective effect of DHEA on the augmented death. The data indicate that DHEA prevents the glucose deprivation-evoked augmented death by inhibiting the production of superoxide anion in immunostimulated C6 glioma cells.

Adjuvants, Immunologic↗
PubMed2001

Iron deficiency anemia increases nitric oxide production in healthy adolescents.

To investigate the influence of iron deficiency and iron supplementation on nitric oxide (NO) production, we measured serum iron markers, serum nitrate and nitrite (NOx) concentrations, reticulocyte maturity index (RMI), and serum transferrin receptor (sTfR) levels in 369 females aged 14-19 years. RMI was analyzed by flow cytometry, sTfR concentrations were measured by enzyme immunoassay, and serum NOx levels were tested by the Griess reaction. NOx concentrations of the subjects in iron depletion phase were significantly higher than those of healthy controls. NOx concentrations increased gradually as iron deficiency progressed and were threefold higher than for the healthy controls, when the subjects attained a frank iron deficiency anemia. In particular, the NOx concentrations were 7.5-fold higher in the patients with severe iron deficiency anemia (Hb<80 g/l) than for the subjects with high hemoglobin value (Hb>or=140 g/l). The increased NOx concentrations (132.6+/-42.1 microM) observed in the group with severe anemia decreased significantly (46.3+/-15.8 microM) after hemoglobin levels were normalized by iron supplementation ( P<0.01). NOx concentrations correlated inversely with hemoglobin levels ( r(2)=0.202, P<0.01), but correlated positively with the sTfR concentrations ( r(2)=0.322, P<0.01) and the RMI ( r(2)=0.369, P<0.01). In conclusion, iron deficiency anemia increases NO production, and elevated NOx concentrations in iron deficiency anemia return to normal with iron supplementation.

Adolescent↗
PubMed2001

Comparison of three techniques to measure unsaturated-zone air permeability at Picatinny Arsenal, NJ.

The purpose of this study is to compare three techniques to measure the air permeability of the unsaturated zone at Picatinny Arsenal, NJ and to examine the effects of moisture content and soil heterogeneity on air permeability. Air permeability was measured in three ways: laboratory experiments on intact soil cores, field-scale air pump tests and calibration of air permeability to air pressures measured in the field under natural air pressure conditions using a numerical airflow model. The results obtained from these three methods were compared and found to be similar. Laboratory experiments performed on intact cores measured air permeability values on the order of 10(-14) to 10(-9) m2. Low-permeability cores were found between land surface and a depth of 0.6 m. The soil core data were divided into two layers with composite vertical permeability values of 1.3 x 10(-13) m2 from land surface to a 0.6-m depth and 3.8 x 10(-10) m2 for the lower layer. Analyses of the field-scale pump tests were performed for two scenarios: one in which the entire unsaturated zone was open to the atmosphere and one assuming a cap of low permeability extending 0.6 m below land surface. The vertical air permeability values obtained for the open scenario ranged from 1.2 x 10(-9) to 1.5 x 10(-9) m2, and ranged from 3.6 x 10(-9) to 6.8 x 10(-9) m2 in the lower layer, assuming an upper cap permeability of 6.0 x 10(-14) m2. The results from the open scenario are much higher than expected and the possible reasons for this ambiguity are discussed. The results from the capped scenario matched closely with those from the other methods and indicated that it is important to have background information on the study site to correctly analyze the pump test data. The optimized fit of the natural subsurface air pressure was achieved with an intrinsic permeability value of 3.3 x 10(-14) m2. When the data were refitted to the model assuming two distinct layers of the unsaturated zone, the optimized fit was achieved with intrinsic air permeabilities of 1.6 x 10(-14) m2 for the upper, low-permeability region and 8.4 x 10(-9) m2 for the lower region. Vertical air-permeability predictions from the three methods are similar provided that soil cores are collected from all representative depths to account for heterogeneous layers and that the correct assumptions are made when analyzing field-scale pump test data.

Air↗
PubMed2001

Immunostimulation of rat primary astrocytes decreases intracellular ATP level.

In this study we investigated the effect of immunostimulation on intracellular ATP level in rat glial cells. Rat primary astrocytes or C6 glioma cells were treated for 48 h with IFN-gamma, LPS or IFN-gamma plus LPS. These treatments increased NO production from the cells and a synergistic increase in NO production was observed with IFN-gamma plus LPS. Intracellular ATP level was decreased to about half the control level at the highest concentration of IFN-gamma (100 U/ml) plus LPS (1 microg/ml) without affecting cell viability. The level of intracellular ATP was inversely correlated with the extent of NO production from the glial cells. The increase in NO production is at least 6 h ahead of the initiation of ATP depletion, and NOS inhibitor N(G)-nitro-L-arginine (NNA) or Nomega-nitro-L-arginine methyl ester (L-NAME) inhibited NO production and ATP depletion. Exogenous addition of peroxynitrite generator 3-morpholinosydnonimine (SIN-1) and to a lesser extent NO generator S-nitroso-N-acetylpenicillamine (SNAP) depleted intracellular ATP level in a dose-dependent manner. The results from the present study imply that immunostimulation of rat glial cells decreases the intracellular ATP level without affecting cell viability. Considering the role of astrocytes as an essential regulator of the extracellular environment in the brain, the immunostimulation-induced decrease in intracellular ATP level may participate in the pathogenesis of various neurological diseases.

Adenosine Triphosphate↗
PubMed2001

F508 amino acid deletion mutation of CFTR gene in Korean lung cancer patients.

Mutations of the transmembrane conductance regulator (CFTR) gene in cystic fibrosis lead to dysfunction of the lung, pancreas, and sweat glands, etc. To investigate the possibility of the relationship between lung cancer and the mutations of CFTR gene, we determined amino acid sequences using reverse transcription-polymerase chain reaction (RT-PCR) and DNA sequencing. In this study, the deletion mutation of 508th amino acid in one of nine lung caner patients was found confirming that CFTR gene mutation exists in a Korean lung cancer patient.

Adult↗
PubMed2001

Reticulocyte subpopulations and reticulocyte maturity index (RMI) rise as body iron status falls.

To investigate the influence of body iron status on reticulocyte subpopulations and reticulocyte maturity index (RMI), we measured serum iron markers, fluorescent intensity of reticulocytes, and serum transferrin receptor (sTfR) concentrations in 374 females aged 14-19 years. Reticulocyte subpopulations were analyzed by flow cytometry, and sTfR concentration was measured by enzyme immunoassay. There were no significant differences in the values of reticulocyte subpopulations and RMI between ferritin alone-depleted group and healthy controls. However, middle- and high-fluorescence reticulocytes and RMI were significantly higher in both the serum iron- and serum ferritin-depleted groups than in the ferritin alone-depleted group. Middle-fluorescence reticulocytes and RMI increased gradually as the body iron store was depleted and were 3.4- and 3.6-fold higher, respectively, than normal controls, when the subjects attained a frank iron-deficiency anemia. There were no significant changes in the values of red blood cells or total reticulocyte counts during iron-depleted states. The mean value of sTfR (3.98 mg/l) in the subjects with RMI > or = 1.5% was significantly higher than that (2.26 mg/l) in the subjects with RMI < 1.5% (P < 0.01). The sTfR concentration correlated significantly with RMI (r = 0.61, P < 0.01) and middle-fluorescence reticulocytes (r = 0.59, P < 0.01). In short, body iron depletion induces elevation of immature reticulocyte fractions and RMI.

Adolescent↗
PubMed2001

Integrated bioprocessing for plant cell cultures.

Plant cell suspension culture has become the focus of much attention as a tool for the production of secondary metabolites including paclitaxel, a well-known anticancer agent. Recently, it has also been regarded as one of the host systems for the production of recombinant proteins. In order to produce phytochemicals using plant cell cultures, efficient processes must be developed with adequate bioreactor design. Most of the plant secondary metabolites are toxic to cells at the high concentrations required during culture. Therefore, if the product could be removed in situ during culture, productivity might be enhanced due to the alleviation of this toxicity. In situ removal or extractive bioconversion of such products can be performed by in situ extraction with various kinds of organic solvents. In situ adsorption using polymeric resins is another possibility. Using the fact that secondary metabolites are generally hydrophobic, various integrated bioprocessing techniques can be designed not only to lower toxicity, but also to enhance productivity. In this article, in situ extraction, in situ adsorption, utilization of cyclodextrins, and the application of aqueous two-phase systems in plant cell cultures are reviewed.

Acrylic Resins↗
PubMed2001

Apoptosis-Inducing costunolide and a novel acyclic monoterpene from the stem bark of Magnolia sieboldii.

In a course of obtaining more amount of bioactive costunolide and successive phytochemical isolation from Magnolia sieboldii (Magnoliaceae), a novel acyclic monoterpene 1 named deoxygeraniol [2,6(E)-dimethyl-2,6-octadiene] was isolated along with beta-sitosterol 3-O-linoleate (2), trilinolein (3) and high amount of costunolide (4) in the pure state. The structure of compound 1 was determined on the basis of spectroscopic data. Costunolide was found to induce apoptotic cell death in a dose-dependent manner by nucleosomal DNA ladder and flow cytometric analysis. Immunoblot analysis showed that the level of the anti-apoptotic protein, Bcl-2, was decreased, whereas the cleavage of poly-(ADP-ribose) polymerase was activated. Furthermore, the N-acetyl-L-cysteine antioxidant effectively prevented costunolide-induced cytotoxicity. These results suggest that costunolide-induced cell death is mediated by reactive oxygen species

Acetylcysteine↗
PubMed2001

Monoamine oxidase B inhibitors from the fruits of Opuntia ficus-indica var. saboten.

Three varieties of methyl citrate and 1-methyl malate were isolated from the fruits of Opuntia ficus-indica var. saboten Makino through in vitro bioassay-guided isolation for the inhibition on monoamine oxidase(MAO). The IC50 values for MAO-B of 1-monomethyl citrate, 1,3-dimethyl citrate, trimethyl citrate and 1-methyl malate were 0.19, 0.23, 0.61 and 0.25 mM, respectively. However, on MAO-A, their inhibitions showed only marginal activity.

Citric Acid↗
PubMed2001

A new anti-hemoglobin F antibody against synthetic peptides for the detection of F-cell precursors (F-blasts) in bone marrow.

To date there are few antibodies available for the detection of fetal hemoglobin (HbF)-containing erythroblasts (F-blasts) in paraffin-embedded hematopoietic tissues. Recently, we developed a new polyclonal antibody specific to F-blasts by immunization of a rabbit with synthetic peptides of human HbF. Specificity and reactivity of the antibody were confirmed by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. ELISA confirmed that the antibody showed strong immunoreactivity to fetal hemoglobin but no reaction to adult hemoglobin. The antibody could detect the presence of fetal blood hemolysates (10 microg/mL) at a dilution of 10(-5). According to immunohistochemical analysis, there were strong positive reactions to fetal erythroblasts in the liver and the spleen at 29 weeks of gestation and to erythroblasts from patients with myelodysplastic syndromes and erythroleukemia but no reactions to normal adult erythroblasts in bone marrow. Fetal erythrocytes in fetal blood vessels of placental tissues were strictly distinguished from maternal erythrocytes in the same sections by their positive reactions, indicating the presence of HbF. This new antibody will be a useful tool for studying fetal hemoglobin synthesis and for detecting F-blasts in archival specimens of various hematological diseases.

Amino Acid Sequence↗
PubMed2001

Accumulation profiles of persistent organochlorines in waterbirds from an estuary in Korea.

Persistent organochlorine pollutants (POPs), such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and organochlorine (OC) pesticides such as DDTs (dichlorodiphenyltrichloroethane), HCHs (hexachlorocyclohexane isomers), CHLs (chlordane compounds) and HCB (hexachlorobenzene), were measured in subcutaneous fat of resident and migratory birds collected from the Nakdong River estuary (NRE) in Korea. Black-tailed gull, a resident bird from the NRE, contained greater concentrations of PCDD/Fs and PCBs than the migratory birds collected in the estuary. For example, mean concentrations of PCDD/Fs in black-tailed gull (395.5 pg/g fat weight) were higher than those in migratory birds, such as greenshank (198.3 pg/g fat weight), common gull (90.9 pg/g fat weight) black-headed gull (84.2 pg/g fat weight), and common tern (47.1 pg/g fat weight). However, concentrations of DDTs and/or HCHs were great in some migratory species, such as little tern (mean DDT 6,200 ng/g fat weight) and black-necked grebe (HCHs 475 ng/g fat weight). This suggested that contamination of PCDD/Fs and PCBs in resident gulls are due to intake of locally contaminated fish near the NRE. Elevated OC pesticide levels in migratory birds indicated that these birds have been exposed to DDTs and HCHs during their migration in Southeast Asian countries where chlorinated pesticides are still used. 2,3,7,8-Tetrachloro dibenzo-p-dioxin equivalents (TEQs) were calculated using the toxic equivalency factors (TEFs) reported by World Health Organization in 1998. Four of the 2,3,7,8-substituted congeners of PCDD/Fs contributed over 90% of the TEQs.

Adipose Tissue↗