PubMed Health⌕ Search

Biomedical subjects

B Y Lee

Publications and source records attributed to B Y Lee.

At least 19 recordsLinked to original sources
PubMed2001

Induction of cytochrome P450 1A1 gene expression by a vitamin K3 analog in mouse hepatoma Hepa-1c1c7 cells.

Nine vitamin K3 analogs were compared with respect to the induction of the cytochrome P450 1A1 (CYP1A1) expression in mouse hepatoma Hepa-1c1c7 cells. 6-(4-Diethylamino)phenyl-7-chloro-5,8-quinolinedione (EA4) caused a significant induction of the CYP1A1-mediated ethoxyresorufin O-deethylase activity in a time- and concentration-dependent manner. The induction was accompanied by an increase of the Cyp1a1 mRNA transcription. The transient expression of the mouse Cyp1a1-CAT gene into cells showed that EA4 induced CAT activity. However, the aryl hydrocarbon receptor and its nuclear partner, aryl hydrocarbon receptor nuclear translocator mRNA transcription, were unaffected by the EA4 treatment. When the cells were incubated with EA4 in the presence of 1 nM TCDD, the ethoxyresorufin O-deethylase activity that was induced by TCDD was significantly suppressed by EA4. Inhibition of protein synthesis by cycloheximide strongly enhanced the EA4-dependent Cyp1a1 mRNA expression. Up-regulation of protein kinase C by a 2 h preincubation with phorbol 12-myristate 13-acetate increased the EA4-dependent expression of the Cyp1a1 gene. In human cells, such as HepG2 (human hepatocarcinoma), MCF-7 (human breast adenocarcinoma cell line), and HL-60 (human promyelocytic cell line), the expression of CYP1A1 mRNA was also induced by EA4 treatment. Moreover, CYP1B1 mRNA was increased by EA4 in MCF-7 cells. These results indicate that EA4 modulates CYP1A1 and CYP1B1 expressions by transcriptional activation. Also, protein kinase C may be involved in the induction mechanism of CYP1A1 by EA4.

Animals↗
PubMed2001

In vitro development of reconstructed bovine embryos and fate of donor mitochondria following nuclear injection of cumulus cells.

In this study we examined the developmental potential of reconstructed embryos and the fate of donor mitochondria during preimplantation development after nuclear transfer in cattle. Isolated cumulus cells were used as donor cells in nuclear transfer. Cumulus cells labelled with MitoTracker Green FM fluorochrome were injected into enucleated bovine MII oocytes and cultured in vitro. MitoTracker labelling on donor cells did not have a detrimental effect on blastocyst formation following nuclear transfer. Cleavage rate was about 69% (56/81) and blastocyst formation rate was 6.2% (5/81) at 7 days after nuclear transfer. The labelled mitochondria dispersed to the cytoplasm and became distributed between blastomeres and could be identified up to the 8- to 15-cell stage. Small patches of mitochondria were detected in some 8- to 15-cell stage embryos (5/20). However, donor mitochondria were not detected in embryos at the 16-cell stage and subsequent developmental stages. In the control group, mitochondria could be identified in arrested 1-cell embryos up to 7 days after nuclear transfer. These results suggest that disappearance of the labelled donor mitochondria in nuclear transfer bovine embryos is not due to fading of the fluorochrome marker, but is rather an as yet undefined cytoplasmic event.

Animals↗
PubMed2001

Toxicity and biodegradation of products from polyester hydrolysis.

Toxicity of products from polyester hydrolysis such as succinic acid (SA), adipic acid (AA), mandelic acid (MA), terephthalic acid (TA), 1,4-butanediol (1,4-B), ethylene glycol (EG), styrene glycol (SG) and 1,4-cyclohexane dimethanol (1,4-C) was evaluated by phytotoxicity test on germination of young radish seeds and by cytotoxicity test on HeLa cells. The phytotoxicity test revealed SG > MA > 1,4-C > AA approximately SA > TA approximately EG > 1,4-B in order of decreasing toxicity taking into consideration the growth behavior after germination as well as the percentage of germination. Toxicity on HeLa cells decreased in slightly different order compared to that on young radish seeds, i.e. SG > 1,4-C > MA > TA > SA > AA > EG > 1,4-B. Tests for the phytotoxicity and for cytotoxicity indicated that the aromatic compounds were more harmful than the aliphatic ones. Each group of 4 strains which grew most rapidly on each agar plate containing SA, AA, MA, TA, 1,4-B, EG, SG and 1,4-C respectively as a sole carbon source was identified by the fatty acid methyl esters analysis. The modified Sturm test was carried out using the single isolated strain, an activated sludge or a mixed soil to measure the rate of mineralization of the compounds into carbon dioxide. The aliphatic compounds were mineralized more easily than the aromatic compounds. 1,4-C showed the most exceptionally slow degradation. A scrutiny of residual 1,4-C after degradation is required before polyesters containing 1,4-C could be classified into compostable because 1,4-C has detrimental effects on young radish seeds and HeLa cells and has a tendency to accumulate in the environment due to its slow degradability.

Animals↗
PubMed2001

Nutritional disorders among workers in North China during national turmoil.

Previously undescribed disorders of nutrition of thiamin, niacin and pyridoxin were observed among the poor people of North China during periods of prolonged deprivation. These disorders were often elicited or exacerbated by physical exertion. Thiamin deficiency syndromes included great toe pain, heel pain, temporomandibular joint click, and painful click of the knee. Syndromes of niacin deficiency included pellagral scrotal dermatitis, hypersecretion of ear wax, and night terrors. Episodic nocturnal motor hyperfunction was caused by pyridoxin deficiency. Several cases with cardiovascular diseases were observed in which nutritional debt appeared to occur simultaneously with oxygen debt following severe physical labor. Intramuscular thiamin HCl ameliorated symptoms of impending stroke. Persons with the same symptoms who did not receive thiamin progressed to fatal stroke.

Adult↗
PubMed2001

Activation of the IL-10 gene promoter following photodynamic therapy of murine keratinocytes.

Photodynamic therapy (PDT), an anticancer treatment modality, has recently been shown to be an effective treatment for several autoimmune disease models including antigen-induced arthritis. PDT was found to induce the expression of IL-10 messenger RNA (mRNA) and protein in the skin, and this expression has similar kinetics to the appearance of PDT-induced suppression of skin-mediated immune responses such as the contract hypersensitivity (CHS) response. Some aspects of the UVB-induced suppression of the immune response have been linked to the induction of IL-10. IL-10 has been shown to inhibit the development and activation of Th1 cells, which are critical for many cell-mediated immune responses, including CHS. We have examined the effect of PDT and UVB irradiation on the activity of the IL-10 gene promoter and on IL-10 mRNA stability using the murine keratinocyte line, PAM 212. In vitro PDT induces IL-10 mRNA and protein expression from PAM 212 cells, which can be correlated with an increase in AP-1 DNA binding activity and activation of the IL-10 gene promoter by PDT. Deletion of an AP-1 response element from the IL-10 gene promoter was shown to abrogate the PDT-induced promoter activity indicating that the AP-1 response element is critical to IL-10 induction by PDT. In addition, PDT results in an increase in IL-10 mRNA stability, which may also contribute to the increased IL-10 expression in PAM 212 cells following PDT. In vitro UVB irradiation also results in activation of the IL-10 promoter. However, in contrast to PDT, UVB-induced activation of the IL-10 promoter is not AP-1 dependent and did not increase IL-10 mRNA stability.

Animals↗
PubMed2001

Collection efficiency of metallic contaminants on si wafer by vapor-phase decomposition-droplet collection.

The collection efficiency of metallic contaminants on four different types of silicon wafers was investigated. P, p+, n and n(+)-type polished silicon wafers were used for the substrate, and 14 metallic elements (Na, Mg, Al, K, Ca, Cr, Fe, Mn, Co, Ni, Cu, Zn, Mo and Ti) were contaminated on silicon wafer surface. Vapor-phase decomposition-droplet collection (VPD-DC) was employed as the sample preparation procedure. For the collecting solution, HNO3, HF and a mixture of HF and H2O2 were used, respectively. A liquid droplet collecting metallic contaminants during VPD-DC was analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). As a result, it was found that HNO3 and HF were not suitable for collecting Cu. Copper was not collected completely in HNO3 and HF. A mixture of HF and H2O2 is the most effective to collect all of the tested metallic elements, regardless of the dopant concentration and type of substrate.

Journal Article↗
PubMed2001

Frequencies of fetal chromosomal abnormalities at prenatal diagnosis: 10 years experiences in a single institution.

We present frequencies of fetal chromosomal abnormalities in 4,907 prenatal cytogenetic examinations at Samsung Cheil Hospital from 1988 to 1997 for 10 yr duration. Prenatal karyotypes were undertaken in 3,913 amniotic fluid samples, 800 chorionic villi samples, and 194 percutaneous umbilical blood samples. The frequency of fetal abnormal karyotypes was 3.1% (150 cases). Numerical chromosome abnormalities were 87 cases (1.8%) and structural aberrations of chromosomes were 63 cases (1.3%). In the numerical chromosomal abnormalities, the frequency of trisomy 21 was by far the highest (36 cases), followed by trisomy 18 in 22 cases and sex chromosome aneuploidies in 19 cases. In the structural chromosomal aberrations, 5 cases had the inversions in chromosome 2, 7, 17, and Y. Chromosomal deletions in 6 cases and additions in 4 cases were analysed. Of the remaining 47 translocation in abnormal fetuses, reciprocal translocation was in 26 cases and Robertsonian translocation in 21 cases. Among them, 41 cases were balanced translocation and 6 were unbalanced. Thirty five cases of translocation were inherited from one of the parents. Four had de novo chromosome rearrangements, and 8 cases were unknown.

Chromosome Aberrations↗
PubMed2001

Toxoplasma gondii: ultrastructural localization of specific antigens and inhibition of intracellular multiplication by monoclonal antibodies.

This experiment was focused on the characterization of anti-Toxoplasma monoclonal antibodies (mAbs) and the effect of mAbs on the parasite invasion of mouse peritoneal macrophages. Twenty eight mAbs including M110, M556, R7A6 and M621 were characterized by Ab titer, immunoglobulin isotyping and western blot pattern. Antibody titer (optical density) of 4 mAbs, M110, M556, R7A6 and M621, were 0.53, 0.67, 0.45 and 0.39 (normal mouse serum; 0.19) with the same IgG1 isotypes shown by Enzyme-linked immunosorbent assay (ELISA). Western blot analysis showed that M110, M556, R7A6 and M621 reacted with the 33 kDa (p30), 31 kDa (p28), 43 kDa and 36 kDa protein. Immunogold labelling of mAbs M110, M556, R7A6 and M621 reacted with the surface membrane, dense granules and parasitophorous vacuolar membrane (PVM), rhoptries and cytoplasm of tachyzoite, respectively. For in vitro assay, preincubation of tachyzoites with four mAbs, M110, M556, R7A6 and M621 resulted in the decrease of the number of infected macrophages (p < 0.05) and the suppression of parasite multiplication at 18 h post-infection. Four monoclonal antibodies including M110 (SAG1) were found to have an important role in the inhibition of macrophage invasion and T. gondii multiplication in vitro, and these mAbs may be suitable for vaccine candidates, diagnostic kit and for chemotherapy.

Animals↗
PubMed2000

Stress fever magnitude in laboratory-maintained California ground squirrels varies with season.

A previous study demonstrated that California ground squirrels (Spermophilus beecheyi) living in the natural environment had, independent of season, a significantly higher mean diurnal body temperature (T(b)) (39.6 degrees C) than either summer (37.5 degrees C) or winter (36.5 degrees C) laboratory maintained animals. Based upon the previous study it has been suggested that California ground squirrels living in the natural environment may have an elevated set-point for body temperature in a manner analogous to a stress fever response. The present study was conducted to determine if season and/or duration of laboratory open-field exposure influenced the magnitude of laboratory open-field stress fever. If stress fever was involved to some extent in the higher body temperature observed in animals from the natural environment, laboratory maintained animals should exhibit a lower magnitude stress fever during the summer months and a higher magnitude stress fever during the winter months. It was hypothesized that laboratory maintained animals would exhibit the same set-point for stress fever T(b) independent of season, and that the duration of open-field exposure would not influence the magnitude of stress fever. Adult California ground squirrels were acclimated to an ambient temperature of 20+/-1.0 degrees C under either LD 14:10 (summer) or LD 10:14 (winter) photoperiod conditions and individuals from both photoperiod conditions were exposed for periods of 2, 4, and 6 h to an open-field arena. An analysis of the data with a two-factor ANOVA demonstrated that season (photoperiod) significantly influenced the magnitude of the stress fever response (1.1+/-0.1 degrees C for summer animals; 2.1+/-0.2 degrees C for winter animals) while there was no significant influence of open-field exposure duration on stress fever magnitude. These results demonstrate that although the set-point for body temperature in unstressed laboratory maintained California ground squirrels varies with season, the set-point for body temperature in open-field stressed animals does not vary with season. These data lend support to the hypothesis that something like stress fever may play some role in the higher body temperature observed in California ground squirrels living in the natural environment.

Animals↗
PubMed2000

Deviant expression of Rab5 on phagosomes containing the intracellular pathogens Mycobacterium tuberculosis and Legionella pneumophila is associated with altered phagosomal fate.

The intracellular human pathogens Legionella pneumophila and Mycobacterium tuberculosis reside in altered phagosomes that do not fuse with lysosomes and are only mildly acidified. The L. pneumophila phagosome exists completely outside the endolysosomal pathway, and the M. tuberculosis phagosome displays a maturational arrest at an early endosomal stage along this pathway. Rab5 plays a critical role in regulating membrane trafficking involving endosomes and phagosomes. To determine whether an alteration in the function or delivery of Rab5 could play a role in the aberrant development of L. pneumophila and M. tuberculosis phagosomes, we have examined the distribution of the small GTPase, Rab5c, in infected HeLa cells overexpressing Rab5c. Both pathogens formed phagosomes in HeLa cells with molecular characteristics similar to their phagosomes in human macrophages and multiplied in these host cells. Phagosomes containing virulent wild-type L. pneumophila never acquired immunogold staining for Rab5c, whereas phagosomes containing an avirulent mutant L. pneumophila (which ultimately fused with lysosomes) transiently acquired staining for Rab5c after phagocytosis. In contrast, M. tuberculosis phagosomes exhibited abundant staining for Rab5c throughout its life cycle. To verify that the overexpressed, recombinant Rab5c observed on the bacterial phagosomes was biologically active, we examined the phagosomes in HeLa cells expressing Rab5c Q79L, a fusion-promoting mutant. Such HeLa cells formed giant vacuoles, and after incubation with various particles, the giant vacuoles acquired large numbers of latex beads, M. tuberculosis, and avirulent L. pneumophila but not wild-type L. pneumophila, which consistently remained in tight phagosomes that did not fuse with the giant vacuoles. These results indicate that whereas Rab5 is absent from wild-type L. pneumophila phagosomes, functional Rab5 persists on M. tuberculosis phagosomes. The absence of Rab5 on the L. pneumophila phagosome may underlie its lack of interaction with endocytic compartments. The persistence of functional Rab5 on the M. tuberculosis phagosomes may enable the phagosome to retard its own maturation at an early endosomal stage.

Animals↗
PubMed2000

Mycobacterium tuberculosis and Legionella pneumophila phagosomes exhibit arrested maturation despite acquisition of Rab7.

Rab7 is a small GTPase that regulates vesicular traffic from early to late endosomal stages of the endocytic pathway. Phagosomes containing inert particles have also been shown to transiently acquire Rab7 as they mature. Disruption in the pathway prior to the acquisition of Rab7 has been suggested as playing a role in the altered maturation of Mycobacterium bovis BCG phagosomes. As a first step to determine whether disruption in the delivery or function of Rab7 could play a role in the altered maturation of Legionella pneumophila and M. tuberculosis phagosomes, we have examined the distribution of wild-type Rab7 and the GTPase-deficient, constitutively active mutant form of Rab7 in HeLa cells infected with L. pneumophila or M. tuberculosis. We have found that the majority of L. pneumophila and M. tuberculosis phagosomes acquire relatively abundant staining for Rab7 and for the constitutively active mutant Rab7 in HeLa cells that overexpress these proteins. Nevertheless, despite acquisition of wild-type or constitutively active Rab7, both the L. pneumophila and the M. tuberculosis phagosomes continue to exhibit altered maturation as manifested by a failure to acquire lysosome-associated membrane glycoprotein 1. These results demonstrate that L. pneumophila and M. tuberculosis phagosomes have receptors for Rab7 and that the altered maturation of these phagosomes is not due to a failure to acquire Rab7.

Animals↗
PubMed2000

Incidence and significance of demonstrating the meniscofemoral ligament on MRI.

The aim was to evaluate how often MRI can detect the meniscofemoral ligament and if there is any relationship with the presence of lateral meniscal tears. Sagittal and coronal MR images of 138 patients with arthroscopically proven meniscal tears were included in this study. MR images were retrospectively reviewed for the presence of a meniscofemoral ligament and a lateral meniscal tear. The chi 2 test was used for statistical analysis. Either one or both meniscofemoral ligaments were shown in 114 (83%) of 138 patients on MR images. In 61 cases with a lateral meniscal tear, the meniscofemoral ligament was present in 82% (50/61) and absent in 18% (11/61). In 77 cases without lateral meniscal tear, the meniscofemoral ligament was present in 83% (64/77) and absent in 17% (13/77). A significant correlation was not established between the meniscofemoral ligament and lateral meniscal tear (p = 0.85).

Adolescent↗
PubMed2000

Assessment of Nipah virus transmission among pork sellers in Seremban, Malaysia.

Between September 1998 and May 1999, 265 cases of encephalitis were reported from among those involved in pig rearing. A few cases were also reported among abattoir workers. This raised questions of the risk of transmission among those who handled raw pork. A serosurvey was conducted among pork sellers in Seremban town, which is about 20 km from one of the pig rearing areas which had reported cases of encephalitis. It was found that out of the 28 pork sellers tested, only one tested positive for Nipah virus antibodies and that this pork seller also worked in an abattoir in the same district, removing the urinary bladders from slaughtered pigs. Based on these findings, it was concluded that the risk of transmission of the virus from handling raw pork appeared to be low.

Animals↗
PubMed1999

Identification of the yqhE and yafB genes encoding two 2, 5-diketo-D-gluconate reductases in Escherichia coli.

The identification of a gene (yiaE) encoding 2-ketoaldonate reductase (2KR) in our previous work led to the hypothesis that Escherichia coli has other ketogluconate reductases including 2, 5-diketo-D-gluconate reductase (25DKGR) and to study of the related ketogluconate metabolism. By using the deduced amino acid sequences of 5-diketo-D-gluconate reductase (5KDGR) of Gluconobacter oxydans and 25DKGR of Corynebacterium sp., protein databases were screened to detect homologous proteins. Among the proteins of E. coli, an oxidoreductase encoded by yjgU and having 56% similarity to 5KDGR of G. oxydans and two hypothetical oxidoreductases encoded by yqhE and yafB and having 49.8 and 42% similarity, respectively, to 25DKGR of Corynebacterium sp. were detected. Recently, the yjgU gene was identified as encoding 5KDGR and renamed idnO (C. Bausch, N. Peekhaus, C. Utz, T. Blais, E. Murray, T. Lowary, and T. Conway, J. Bacteriol. 180:3704-3710, 1998). The pathways involved in the metabolism of ketogluconate by E. coli have been predicted by biochemical analysis of purified enzymes and chemical analysis of the pathway intermediates. The gene products of yqhE and yafB were identified as 25DKGR-A, and 25DKGR-B, respectively, catalyzing the reduction of 25KDG to 2-keto-L-gulonate (2KLG). The native 25DKGR-A, 25DKGR-B, and 5KDGR had apparent molecular weights of about 30,000, 30,000, and 54,000, respectively. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels, all three enzymes showed protein bands with a molecular weight of about 29,000, which indicated that 25DKGR-A, 25DKGR-B, and 5KDGR may exist as monomeric, monomeric, and dimeric proteins, respectively. The optimum pHs for reduction were 7.5, 7.0, and 8.0, respectively. The 5KDGR was active with NADH, whereas 25DKGR-A and 25DKGR-B were active with NADPH as a preferred electron donor. 25DKG can be converted to 5KDG by 2KR, which is then reduced to D-gluconate by 5KDGR. The pathways were compared with those of Erwinia sp. and Corynebacterium sp. A BLAST search of published and incomplete microbial genome sequences revealed that the ketogluconate reductases and their related metabolism may be widespread in many species.

Base Sequence↗
PubMed1999

Identification of fur, aconitase, and other proteins expressed by Mycobacterium tuberculosis under conditions of low and high concentrations of iron by combined two-dimensional gel electrophoresis and mass spectrometry.

Iron plays a critical role in the pathophysiology of Mycobacterium tuberculosis. To gain a better understanding of iron regulation by this organism, we have used two-dimensional (2-D) gel electrophoresis, mass spectrometry, and database searching to study protein expression in M. tuberculosis under conditions of high and low iron concentration. Proteins in cellular extracts from M. tuberculosis Erdman strain grown under low-iron (1 microM) and high-iron (70 microM) conditions were separated by 2-D polyacrylamide gel electrophoresis, which allowed high-resolution separation of several hundred proteins, as visualized by Coomassie staining. The expression of at least 15 proteins was induced, and the expression of at least 12 proteins was decreased under low-iron conditions. In-gel trypsin digestion was performed on these differentially expressed proteins, and the digestion mixtures were analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry to determine the molecular masses of the resulting tryptic peptides. Partial sequence data on some of the peptides were obtained by using after source decay and/or collision-induced dissociation. The fragmentation data were used to search computerized peptide mass and protein sequence databases for known proteins. Ten iron-regulated proteins were identified, including Fur and aconitase proteins, both of which are known to be regulated by iron in other bacterial systems. Our study shows that, where large protein sequence databases are available from genomic studies, the combined use of 2-D gel electrophoresis, mass spectrometry, and database searching to analyze proteins expressed under defined environmental conditions is a powerful tool for identifying expressed proteins and their physiologic relevance.

Aconitate Hydratase↗
PubMed1999

T-cell epitope mapping of the three most abundant extracellular proteins of Mycobacterium tuberculosis in outbred guinea pigs.

The three most abundant extracellular proteins of Mycobacterium tuberculosis, the 30-, 32-, and 16-kDa major extracellular proteins, are particularly promising vaccine candidates. We have mapped T-cell epitopes of these three proteins in outbred guinea pigs by immunizing the animals with each protein and assaying splenic lymphocyte proliferation against a series of overlapping synthetic peptides covering the entire length of the mature proteins. The 30-kDa protein contained nine immunodominant epitopes, the 32-kDa protein contained two immunodominant epitopes, and the 16-kDa protein contained a highly immunodominant region at its N terminus. The immunodominant epitopes of the 30- and 32-kDa proteins in outbred guinea pigs were frequently identified in healthy purified-protein-derivative-positive or BCG-vaccinated individuals in previous studies. The immunodominant epitopes of these major extracellular proteins have potential utility in an epitope-based vaccine against tuberculosis.

Amino Acid Sequence↗