Search PubMed⌕ Search

Biomedical subjects

H Lee

Publications and source records attributed to H Lee.

At least 145 records · Page 8Linked to original sources
PubMed2001

Thioredoxin-linked lipid hydroperoxide peroxidase activity of human serum albumin in the presence of palmitoyl coenzyme A.

Human Serum Albumin (HSA) exerted a significant lipid peroxidase activity with the use of a thiol-reducing equivalent such as dithiothreitol (DTT). Carboxyl group-modified HSA (CM-HSA) showed a 10-fold stronger lipid peroxidase activity (1.6 nmol/min/mg) than that of HSA (0.17 nmol/min/mg). Instead of DTT, thioredoxin (Trx) also supported reducing equivalent to the reduction of lipid hydroperoxide by CM-HSA. Contrast to CM-HSA, HSA did not reduce lipid peroxide with the use of Trx. In the presence of palmitoyl coenzyme A (palmitoyl-CoA) however, HSA used Trx as an electron donor to the reduction of lipid hydroperoxide. The Trx-linked peroxidase activity of HSA sharply increased with elongation in the carbon chain of the acyl moiety of acyl-CoA, showing an optimum activity in the presence of palmitoyl-CoA. Fluorescence study indicates the conformational changes of HSA induced by palmitoyl-CoA. Together, these data suggest that palmitoyl-CoA-bound HSA has a capability to remove lipid peroxide with the use of electrons given by Trx system.

Dithiothreitol↗
PubMed2001

Molecular structures of carbonyl-linked bis(dioxolene) complexes: can a carbonyl group act as an effective ferromagnetic coupler?

Molecular structures of two bis(ZnIIdioxolene) complexes are described: (TpCum,MeZn)(2)1-H2 (C106H123.50B2N12O10Zn2), tetragonal, P4/ncc, a = 25.1810(2) A, b = 25.1810(2) A, c = 34.7744(2) A, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, Z = 8; (TpCum,MeZn)(2)1-H (C101H120B2N12O6Zn2), triclinic, P1, a = 13.6624(2) A, b = 13.80920(10) A, c = 26.62340(10) A, alpha = 96.6910(10) degrees, beta = 91.8560(10) degrees, gamma = 109.0190(10) degrees, Z = 2. One of the complexes, (TpCum,MeZn)(2)1-H2, has two protonated catecholate ligands, while the other complex, (TpCum,MeZn)(2)1-H, has one protonated catecholate and one semiquinone ligand. When reacted with PbO2, a labile S = 1, bis(ZnIIsemiquinone) complex is formed in which the two semiquinones are attached to a common carbonyl group.

Journal Article↗
PubMed2001

p300 does not require its acetylase activity to stimulate p73 function.

We previously reported that p73, like p53, utilizes p300 or cAMP-response element-binding protein-binding protein as its coactivator. Here, we extended this work by further examining whether the intrinsic acetylase activity of p300 is necessary for stimulating p73 function. Although p300 acetylated the C-terminal fragment of p73 (amino acids 311-636) in vitro, it was unable to efficiently acetylate the full-length p73. Consistently, p300 did not acetylate p73 in vivo when both the proteins were overexpressed in cells. Also, an acetylase-defective mutant p300 named p300AT2 was able to elevate p73-dependent transcription in cells. p300 associated with p73 when forming DNA-protein complexes and stabilized p73 proteins. These results demonstrate that p300 does not need its acetylase activity to be a coactivator of p73.

Acetylation↗
PubMed2001

Benzo[g,h,i]perylene synergistically transactivates benzo[a]pyrene-induced CYP1A1 gene expression by aryl hydrocarbon receptor pathway.

Although benzo[g,h,i]perylene (BghiP) has been found to promote the carcinogenesis of benzo[a]pyrene (BaP) in animal models, not much is known about this cocarcinogenic mechanism. In this study, human hepatoma HepG2 cells cotreated with BaP and BghiP were used as a model to investigate the cocarcinogenic mechanism of BghiP in BaP-induced carcinogenesis. DNA adduct formation is thought to initiate carcinogenesis, so the effect of BghiP on BaP-DNA adduct formation was evaluated using a (32)P-postlabeling assay. The BaP-DNA adduct levels increased following the addition of BghiP, in a dose-dependent manner. However, no adducts were formed with BghiP alone. Our previous report showed that cytochrome P450 1A1 (CYP1A1) is responsible for the metabolic activation of BaP and the formation of B[a]P adduct in HepG2 cells. Western blot and Northern blot analyses were used to evaluate whether BaP-induced CYP1A1 protein and mRNA levels increased following the addition of BghiP. Our data showed that BghiP enhanced BaP-induced CYP1A1 protein and its mRNA levels. To understand whether BghiP enhances BaP-induced CYP1A1 gene expression through the aryl hydrocarbon receptor (AhR) signaling pathway, a gel retardation assay was performed to elucidate the synergistic mechanism of BghiP in BaP-induced CYP1A1 gene expression. The results showed that BghiP causes an increase in the nuclear accumulation of AhR in cells and/or activation of AhR to a DNA-binding form. There was a concordant increase in the transcription activation of CYP1A1 gene and the induction of AhR signal pathway. Our findings demonstrated that BghiP enhances BaP-induced CYP1A1 transcription by AhR activation and suggested that the induction mechanism of CYP1A1 contributes to the cocarcinogenic potential of BghiP in BaP-induced carcinogenesis.

Autoradiography↗
PubMed2001

Metabolic characterization of spinocerebellar ataxia type 6.

BACKGROUND: Spinocerebellar ataxia type 6 (SCA6) is a neurodegenerative disorder characterized by slowly progressive ataxia and dysarthria. The mutational basis is an expanded CAG repeat sequence within the coding regions of the CACNL1A4 gene. Basic clinical, neuroimaging, and pathological, and epidemiological features have been described in the literature. However, the metabolic features of SCA6 have not been elucidated. OBJECTIVE: To investigate the metabolic features of SCA6. PATIENTS AND METHODS: Seven patients with SCA6 and 7 healthy individuals underwent positron emission tomography using fluorodeoxyglucose F 18. RESULTS: Cerebral glucose utilization in the 7 patients with SCA6 was characterized by significant hypometabolism in widespread structures, including cortical regions and basal ganglia, as well as the cerebellar hemispheres and brainstem. CONCLUSIONS: The results of the multiple-regional brain hypometabolism suggest that brain dysfunction associated with SCA6 may not be limited to the cerebellum and inferior olive, as previously suggested by the results of other pathologic studies.

Adult↗
PubMed2001

Bilateral sudden deafness as a prodrome of anterior inferior cerebellar artery infarction.

BACKGROUND: Acute ischemic stroke in the distribution of the anterior inferior cerebellar artery is known to be associated with hearing loss, facial weakness, ataxia, nystagmus, and hypalgesia. There have been few reports on bilateral deafness and vertebrobasilar occlusive disease. Furthermore, previous reports have not emphasized the inner ear as a localization of bilateral deafness. OBJECTIVE: To describe the presentation of acute ischemic stroke in the distribution of the anterior inferior cerebellar artery as sudden bilateral hearing loss with minimal associated signs. DESIGN AND SETTING: Case report and tertiary care hospital. PATIENT: A 66-year-old man with diabetes mellitus developed sudden bilateral deafness, unilateral tinnitus, and vertigo 7 days before the onset of dysarthria, facial weakness, and ataxia. T2-weighted magnetic resonance imaging scans showed hyperintensities in the right lateral pons and right middle cerebral peduncle and a possible abnormality of the left middle cerebellar peduncle. A magnetic resonance angiogram showed moderately severe stenosis of the distal vertebral artery and middle third of the basilar artery. The patient's right limb coordination and gait improved steadily over several weeks, but there was no improvement in hearing in his right ear. CONCLUSIONS: The relatively isolated onset of deafness as well as the severity and persistence of the hearing loss led us to conclude that the hearing loss in this case was likely due to prominent hypoperfusion of the internal auditory artery, with labyrinthine infarction as the earliest event. Vertebrobasilar occlusive disease should be considered in the differential diagnosis of sudden bilateral deafness.

Aged↗
PubMed2001

A Hydrogen-Bonded [(Mercuracarborand-Water)2 -Benzene] π-Sandwich Complex.

Two cyclic Lewis acidic receptors, namely B-hexamethyl-9-mecuracarborand-3, [9,12-(CH3 )2 -C2 B10 H8 Hg]3 , each host a single water molecule. A benzene molecule is situated between the two complexed water molecules in a sandwich fashion that suggests there is O-H⋅⋅⋅π hydrogen bonding.

carboranes↗
PubMed2001

In vivo and in vitro proton NMR spectroscopic studies of thiamine-deficient rat brains.

Thiamine deficiency (TD) in rats produces lesions similar to those found in humans with Wernicke's encephalopathy, an organic mental disorder associated with alcoholism. Male Sprague-Dawley rats (n = 24) were deprived of thiamine in a regimen of thiamine-deficient chow and daily intraperitoneal injections of the thiamine antagonist pyrithiamine hydrobromide for 12 days (0.5 mg/kg). In rats with TD, significant changes were observed in the choline peak (reduction and dose-dependent recovery after thiamine replenishment), which was confirmed by the extraction study. Changes were mainly due to the reduction in glycerophosphorylcholine (GPC), suggesting that a reduction in GPC may be relevant to the primary biochemical lesion in TD. These data are compatible with the hypothesis that a decrease in choline compounds is the cause of the biochemical abnormalities that precede neuroanatomic damage characteristic of Wernicke's encephalopathy.

Animals↗
PubMed2001

Protein profiles of the Chinese hamster ovary cells in the resting and proliferating stages.

Identification and characterization of the proteins that regulate the transition from the resting stage (G0) through G1 to S phase of the cell cycle are of central importance to understand the control of cell proliferation and chromosome replication. Unlike in lower organisms, where relatively small numbers of key factors are involved in this process, the factors involved in the same control mechanisms in mammalian systems are much more complex. Furthermore, accumulating lines of evidence now suggest that the nuclear matrix and chromatin organization also play an essential role for the cell cycle control in mammalian cells. To gain a better understanding of the overall dynamics and changes of the protein factors in the context of matrix/chromatin organization, we examined the protein profiles of the Chinese hamster ovary (CHO) cells in different cell cycle compartments. The methods used in this study included subcellular fractionations (cytosol, nuclear extraction, chromatin, and nuclear matrix), two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), silver staining, and immunoblotting. As expected, significant changes of protein profiles were observed when cells entered into proliferating stages from G0. Among approximately 1200 protein spots analyzed by 2-D PAGE, at least 12 showed marked increase or decrease at this transitional period. Further cell-cycle progression from G1 to S phase showed less dramatic changes of overall protein protile. However, the profile of certain proteins showed rather dramatic changes of their subcellular localization during this transitional period. In particular, the levels of proliferating cell nuclear antigen (PCNA) in the nuclear matrix and chromatin dramatically increased in mid-G1 and in the beginning of S phase, respectively, while the overall PCNA level was relatively constant throughout the cell cycle.

Animals↗
PubMed2001

Gender difference in DNA adduct levels among nonsmoking lung cancer patients.

Lung cancer is the leading cause of cancer mortality in Taiwanese women. Cigarette smoking cannot explain the high lung cancer mortality in this population because less than 10% of women in Taiwan are smokers. Therefore, environmental factors other than smoking may play an important role in lung cancer development in female nonsmokers. The purpose of this study was to elucidate the role of environmental carcinogen exposure in lung cancer development in Taiwanese female nonsmokers, based on DNA adduct formation. We collected nontumorous lung tissues resected from 62 nonsmoking lung cancer patients and 20 noncancer controls to investigate whether differences in susceptibility to DNA adduct formation exist between men and women. (32)P-postlabeling and ELISA (enzyme-linked immunosorbent assay) with polyclonal antibody against BPDE (7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene)-DNA adduct were used to evaluate DNA adduct levels in lung tissues of study subjects. Our data showed that the DNA adduct levels of lung cancer patients determined by both assays were significantly higher than those of noncancer controls (P = 0.0001 for (32)P-postlabeling; P = 0.01 for ELISA). Moreover, DNA adduct levels in females were markedly greater than those in males (P = 0.014 for (32)P-postlabeling; P = 0.001 for ELISA). The difference in DNA adduct levels could not be explained by genetic polymorphisms of cytochrome P-4501A1 (CYP1A1) or glutathione S-transferase (GSTM1), as determined by polymerase chain reaction and restriction fragment length polymorphism. These results demonstrate that lung cancer patients have a higher susceptibility to DNA damage than that of noncancer controls. In addition, differences in susceptibility to DNA damage derived from environmental carcinogen exposure were observed between male and female nonsmokers. In conclusion, high susceptibility to DNA damage in females may partially explain the high mortality rate of lung cancer in nonsmoking Taiwanese women.

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

Expression of the seqA gene is negatively modulated by the HU protein in Escherichia coli.

The SeqA protein acts as a regulator of chromosomal replication initiation in Escherichia coli by sequestering hemi-methylated oriC, effectively blocking methylation and therefore preventing rapid re-initiation. The level of SeqA protein is maximal at mid-log phase and decreases when cells enter late-log phase. In hup mutants that lack the HU protein, the maximal seqA expression is also seen at mid-log phase, but seqA expression, as well as SeqA levels and activity, is increased by up to four fold relative to that in the wild type. These results suggest that the HU protein functions as a negative modulator of seqA expression.

Bacterial Outer Membrane Proteins↗
PubMed2001

Introduction of green fluorescent protein gene into phenol-degrading Alcaligenes faecalis cells and their monitoring in phenol-contaminated soil.

Alcaligenesfaecalis (CCT 7145) was isolated from an Amazonian soil sample after an enrichment process to select for phenol-degrading microorganisms. The isolate was labeled with the green fluorescent protein (gfp) gene. The gfp-transformed cells were easily detected using a hand-held UV transilluminator and their taxonomy was confirmed by 16S rRNA sequencing. Polymerase chain reaction (PCR) and Southern blot analyses confirmed that the gfp gene was integrated into the chromosome. The addition of the gfp marker did not affect phenol degradation ability compared with the wild-type. Both, wild-type and gfp-marked A. faecalis cells encapsulated in alginate, tolerated 1,700 microg ml(-1) phenol in liquid medium compared with 1,100 microg ml(-1) phenol for free cells. 14C-Phenol mineralization in soil microcosms was also enhanced by inoculation with encapsulated cells. Survival of gfp-marked cells in phenol-contaminated soil over 22 days was determined from plate counts using an epifluorescence microscope.

Alcaligenes↗
PubMed2001

Urinary 1-hydroxypyrene and 2-naphthol concentrations in male Koreans.

OBJECTIVE: Urinary 1-hydroxypyrene (1-OHP) has been used as a biological marker of exposure to polycyclic aromatic hydrocarbons (PAHs), and urinary 2-naphthol is suggested as a new marker for route-specific exposure to airborne PAHs. We analyzed urinary 1-OHP and 2-naphthol concentrations in 292 male Koreans (129 university students and 163 shipyard workers) to define the distribution pattern in Koreans with no or low occupational exposure to PAHs. METHOD: Histories of cigarette smoking and the eating of PAH-containing foods were obtained by a self-administered structured questionnaire. Urine samples were collected and urinary 1-OHP and 2-naphthol concentrations were measured using high-performance liquid chromatography (HPLC). RESULTS: The arithmetic (geometric) means of urinary 1-OHP and 2-naphthol concentrations for all students, expressed as micromoles per mole of creatinine, were 0.04 (0.04) and 3.12 (2.22), for non-smokers 0.03 (0.03) and 1.78 (1.30) and for smokers 0.05 (0.03) and 4.36 (3.62), respectively. Among shipyard workers, the arithmetic (geometric) means of urinary 1-OHP and 2-naphthol concentrations were 0.69 (0.31) and 4.37 (2.62) for all, 0.27 (0.18) and 2.46 (1.16) for nonsmokers, and 0.97 (0.44) and 5.60 (4.44) for smokers, respectively. Mean urinary 1-OHP and 2-naphthol concentrations differed significantly between nonsmokers and smokers both in students and in shipyard workers. In smokers, some variables related to smoking habit were positively correlated with urinary 1-OHP and with 2-naphthol concentrations. The latter showed better correlations with the variables related to smoking amount than the former. None of the food-related factors was significantly correlated with urinary 1-OHP or 2-naphthol concentration. CONCLUSION: These results suggest that urinary 2-naphthol concentration is more sensitively affected by smoking status than urinary 1-OHP concentration and that urinary 2-naphthol is a sensitive marker for low-level inhalation of PAHs.

Chromatography, High Pressure Liquid↗
PubMed2001

Evaluation of the efficacy of the combination of multiple autoantibodies to islet-specific antigens in Korean type 1 diabetic patients.

With the recent cloning and recombinant expression of novel islet autoantigens, it is possible to investigate whether the quantitative expression of autoantibodies to these molecules is correlated with the semiquantitative titration of islet cell antibodies (ICA). To estimate the regional difference in the degree of association between these autoantibodies, autoantibodies reacting with ICA512/IA-2 (ICA512) and GAD65 in addition to ICA were analyzed in 131 Korean children with type 1 diabetes. Among the 131 type 1 diabetes patients, 36% was ICA512-positive, 56% was anti-GAD65-positive, and 43% was ICA-positive. However, in a subset of these with recent onset (<1 year), the prevalences of ICA512, anti-GAD65, and ICA were 75%, 75%, and 87.5%, respectively. ICA512 as well as anti-GAD65 were significantly associated with the presence of ICA. Among type 1 diabetes patients, 69% had one or more and 43% had two or more of these autoantibodies. Autoantibodies to ICA512 and anti-GAD65 were observed in 40 and in 41 of 56 ICA-positive subjects, respectively. Furthermore, ICA512 or anti-GAD65 were positive in 97% (34 of 35) and 100% (22 of 22) of patients with ICA levels > or =20 JDF-u and > or =40 JDF-u, respectively. The titer of ICA correlated with those of ICA512 (r=0.41, p<0.001) and anti-GAD65 (r=0.49, p<0.001). Both the prevalences and the titers of ICA512 or anti-GAD65 were strongly correlated with those of ICA even in Korean type 1 diabetes patients. ICA512 and anti-GAD65 in combination may be considered to be an alternative to ICA.

Adolescent↗
PubMed2001

The emergence of erythromycin-resistant Streptococcus pyogenes in Seoul, Korea.

High frequencies of erythromycin-resistant streptococci were reported in Japan in the mid-1970s, and in Finland in the late 1980s, related to an increase in the consumption of macrolide antibiotics in these countries. The frequency of erythromycin-resistant Streptococcus pyogenes was reported to be only 2% in 1994, but we know that the susceptibility of the strains to antibiotics had not been tested routinely. We studied the resistance rates of Streptococcus pyogenes to various antibiotics in Seoul, Korea, where antibiotics could be purchased without prescription. From January through December, 1998, 92 isolates of group A streptococci were collected from inpatients and outpatients with pharyngotonsillitis or invasive streptococcal infections, from institutions in five different geographic areas of Seoul; one pediatric clinic, three university hospitals, and one general hospital. All isolates were serotyped by T-agglutination, and minimum inhibitory concentrations (MICs) were determined by agar dilution methods, according to the guidelines of the National Committee for Clinical Laboratory Standards (NCCLS). The most common T-serotype was T12 (44.6%), followed by T4 (19.6%). All the isolates tested were susceptible to penicillin, vancomycin, and cefotaxime. However, 38 isolates (41.3%) were resistant to erythromycin, 32 (34.8%) were resistant to clindamycin, and 48 (52.1%) were resistant to tetracycline. Twenty-seven of 41 isolates serotyped T12 and 3 of 18 isolates serotyped T28 were multiresistant to erythromycin, clindamycin, and tetracycline. Almost half of the isolates obtained from the five different areas in Seoul showed erythromycin resistance in Streptococcus pyogenes. Routine monitoring of antibiotic susceptibility tests and further extensive nationwide surveys are needed to determine the frequency and the extent of the spread of resistant strains in various geographic regions in Korea.

Adolescent↗