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Biomedical subjects

I S Kim

Publications and source records attributed to I S Kim.

At least 55 records · Page 3Linked to original sources
PubMed2001

Activity monitoring for nitrifying bacteria by fluorescence in situ hybridization and respirometry.

The activities of two families of nitrifying bacteria were measured by applied respirometer and fluorescence in situ hybridization (FISH) for the purpose of monitoring nitrogen removal. Oxygen uptake rates (OUR) for Nitrosomonas and Nitrobacter were separately measured with the dosing of selective inhibitors during respirometric monitoring. The FISH method was applied to analyze microorganism communities. In 5 mg NH4+-N/L solution, the total nitrogen oxygen demand (NOD) was found to be 6,672 mg DO/L-day with ammonia and nitrite oxidation rate of 4,512 and 2,160 mg DO/L-day, respectively. The oxygen consumption by endogenous oxidation was 288 mg DO/L-day and the biological oxygen demand 936 mg DO/L-day. Respirometric measurements were well matched by the FISH result, which described the presence and quantity of each nitrifying bacteria as nitrification proceeded. It was found that when coupled with OUR data, FISH could provide valuable information about the nitrogen removal process in many practical wastewater treatment systems.

Ammonia↗
PubMed2001

Effects of continuous and intermittent exposure of lactating mothers to aroclor 1242 on testicular steroidogenic function in the adult male offspring.

Polychlorinated biphenyls (PCBs) are worldwide pollutants and have caused hazardous effects on many animal species including humans. They have been detected in human milk and therefore exposure of newborns to PCBs is unavoidable if they are breast-fed. We present our findings on two experiments performed to test the effects of intermittent and continuous exposure of lactating rats to two different doses (80 microg and 8 microg) of Aroclor 1242 (a PCB congener) on testicular steroidogenic function of their adult male offspring. In experiment I, three groups of lactating dams received daily subcutaneous (SC) injections of either corn oil, 80 microg of Aroclor 1242 and 8 microg of Aroclor 1242 in corn oil, respectively. In experiment II, three groups of lactating dams received two SC injections per week of either corn oil or Aroclor 1242 (80 microg and 8 microg) in corn oil, respectively. Pups in all groups (n=8 per group) were weaned at day 21 and were raised on a normal diet until sacrificed at 90 days. Experiment I: Leydig cell number per testis was significantly (P<0.05) increased and the average volume of a Leydig cell was significantly (P<0.05) reduced in both groups of Aroclor-exposed rats compared to corn oil controls. Both doses of Aroclor resulted in reduced (P<0.05) serum testosterone levels compared to corn oil-treated controls. LH-stimulated testosterone production per testis and per Leydig cell was lower in Aroclor-exposed rats compared to controls. Experiment II: No changes were observed in Leydig cell size and number per testis among the three groups. Serum LH, testosterone and LH-stimulated testicular testosterone production in offspring rats of Aroclor-treated dams were not significantly different (P>.05) from the offspring of corn oil-treated dams. However, these parameters were lower in value in the offspring of dams treated with Aroclor 80 microg compared to the other two groups. LH-stimulated testosterone secretory capacity per Leydig cell was significantly lower in offspring of dams treated with Aroclor compared to controls. Serum T4 and T3 levels were not significantly different among the Aroclor-exposed and control rats in both experiments. These results demonstrate that continuous exposure of lactating mothers to 8 and 80 microg of Aroclor 1242 causes hypotrophy and malfunctioning of Leydig cells in the adult male offspring resulting in a hypoandrogenic status. Intermittent treatment of lactating mothers with 80 microg of Aroclor (but not with 8 microg of Aroclor) also produced malfunctioning of Leydig cells and a hypoandrogenic status in the absence of Leydig cell hypotrophy. However, the Aroclor 8 microg dose was ineffective to produce the above effects.

Age Factors↗
PubMed2001

Quantification of polynuclear aromatic hydrocarbons in transformer oils by enzyme immunoassay.

Many polynuclear aromatic hydrocarbons (PAHs) are either known or suspected carcinogens and are a common constituent of mineral oils. Due to the large number of possible PAH structures, standard quantification methods fail since they either lack specificity or are too complex, requiring individual fractionation, identification, and quantification. A rapid, low-cost, novel analytical screening method, incorporating a silica-based solid-phase extraction (SPE) method linked to co-solvent dilution and quantification of total and carcinogenic PAH levels by immunoassay, is reported here. The method yielded high extraction efficiencies and minimal matrix effects. This novel approach yielded total and carcinogenic PAH levels x 5.7 and x 126, respectively, lower than that recorded by the industry-recognised BS2000 Pt. 346 (IP346) method which estimates the polyaromatic carbon (PAC) content of oils by gravimetry. The method is expected to be of benefit where an indication of PAH levels in oils is important for purchasing, management or disposal purposes and also for risk assessment and for appropriate labelling of oils in line with current legislation.

Carcinogenicity Tests↗
PubMed2001

Microtubule- and dynein-mediated movement of Orientia tsutsugamushi to the microtubule organizing center.

The host cell microfilaments and microtubules (MTs) are known to play a critical role in the life cycles of several pathogenic intracellular microbes by providing for successful invasion and promoting movement of the pathogen once inside the host cell cytoplasm. Orientia tsutsugamushi, an obligate intracellular bacterium, enters host cells by induced phagocytosis, escapes to the cytosol, and then replicates in the cytosol. ECV304 cells infected with O. tsutsugamushi revealed the colocalization of the MT organizing center (MTOC) and cytosolic orientiae by indirect immunofluorescence assay. Using immunofluorescence microscopy in the presence and absence of MT-depolymerizing agents (colchicine and nocodazole), it was shown that the cytosolic oriential movement was mediated by MTs. By transfection study (overexpression of dynamitin [also called p50], which is known to associate with dynein-dependent movement), the movement of O. tsutsugamushi to the MTOC was also mediated by dynein, the minus-end-directed MT-related motor. Although the significance of this movement in the life cycle of O. tsutsugamushi was not proven, we propose that the cytosolic O. tsutsugamushi bacteria use MTs and dyneins to propel themselves from the cell periphery to the MTOC.

Cell Line↗
PubMed2001

Expression of chemokine genes in human dermal microvascular endothelial cell lines infected with Orientia tsutsugamushi.

Scrub typhus, caused by Orientia tsutsugamushi, is characterized by local as well as systemic inflammatory manifestations. The main pathologic change is focal or disseminated multiorgan vasculitis, which is caused by the destruction of endothelial cells and perivascular infiltration of leukocytes. We investigated the regulation of chemokine induction in transformed human dermal microvascular endothelial cells (HMEC-1) in response to O. tsutsugamushi infection. The monocyte chemoattractant protein-1 (MCP-1) and interleukin 8 (IL-8) mRNAs were induced, and their levels showed a transitory peak at 3 and 6 h, respectively. The RANTES transcript was detected at 6 h after infection, with increased levels evident by 48 h. The induction of the MCP-1 and IL-8 genes was not blocked by cycloheximide, suggesting that de novo protein synthesis of host cell proteins is not required for their transcriptional activation. Heat- or UV-inactivated O. tsutsugamushi induced a similar extent of MCP-1 and IL-8 responses. The induction of MCP-1 and IL-8 transcripts in the endothelial cells by O. tsutsugamushi was not blocked by the inhibitors of NF-kappaB. Furthermore, the activation of NF-kappaB was not detected in HMEC-1 stimulated with O. tsutsugamushi. These results demonstrate that heat-stable molecules of O. tsutsugamushi induce the MCP-1 and IL-8 genes and the induction of the chemokine genes may be mediated by an NF-kappaB independent mechanism. We also showed that another major transcription factor, activator protein-1 (AP-1), was up-regulated in HMEC-1 after O. tsutsugamushi infection. This suggests the possible involvement of AP-1 in the chemokine gene expression.

Cells, Cultured↗
PubMed2001

Effects of seasoning and heating device on mutagenicity and heterocyclic amines in cooked beef.

Pan-roasted beef showed a lower mutagenicity after various degrees of cooking than charcoaled one. The high mutagenicity of charcoaled beef was due to the formation of more heterocyclic amines, especially AalphaC (2-amino-9H-pyrido- [2,3-b]indole) and PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) because of rapid and direct heating on the surface of the meat at a high temperature. Seasoning decreased mutagenicity of pan-roasted beef except the very well done sample with unchanged heterocyclic amine contents, but increased mutagenicity of charcoaled beef with decreased levels of AalphaC and PhIP, probably due to the change of heterocyclic amine precursors or alternatively to the occurrence of other mutagens.

Animals↗
PubMed2001

Seasonal changes of testicular weight, sperm production, serum testosterone, and in vitro testosterone release in Korean ring-necked pheasants (Phasianus colchicus karpowi).

To study the biology of reproduction of male Korean ring-necked pheasants kept under natural conditions of temperature and photoperiod, testicular weight, serum testosterone concentrations, testosterone release from the luteinizing hormone (LH)-stimulated testis in vitro and sperm production were measured. Significant changes associated with seasonal cycles were found. Testis weight decreased dramatically in August, remained low until February, rapidly increased from March to high levels to June, and decreased subsequently. Serum testosterone concentrations remained little from August until February, but increased sharply in March to reach the highest levels in April. Thereafter, the concentrations decreased significantly from June. The testosterone release was low from August to February, increased abruptly in March to reach the highest levels in May, and showed rapid decrease thereafter. Sperm production decreased to nondetectable levels from August to February, increased markedly in March, reached a peak in May, and sharply decreased thereafter. Thus, the pheasants breed from late March to late June. These results indicate that the Korean ring-necked pheasant, under natural conditions, exhibits characteristics of a seasonal cycle in reproduction.

Animals↗
PubMed2001

Effects of exposure of lactating female rats to polychlorinated biphenyls (Pcbs) on testis weight, sperm production and sertoli cell numbers in the adult male offspring.

To investigate the effects of intermittent and continuous exposure of lactating rats to Aroclor 1242 (a PCB congener), testis weight, daily sperm production (DSP) and Sertoli cell number per testis were examined in the adult male offspring. Thyroxine (T4) was also measured because of the well-documented effects of polychlorinated biphenyls (PCBs) on this hormone. In experiment 1.3 groups of lactating female rats received daily subcutaneous injections of low (0.8 mg) or high (1.6 mg) doses of Aroclor 1242 in 0.1 ml corn oil from parturition to weaning of pups at 21 days. In experiment II, 3 groups of lactating rats received 2 subcutaneous injections per week of 0.8 or 1.6 mg Aroclor 1242, as in experiment 1. In both experiments, control rats received vehicle alone. Serum T4 was measured at 21 and 90 days of age, and testis weight, DSP and Sertoli cell numbers were examined at 90 days. In experiment I (continuous exposure), both the low (0.8 mg) and high (1.6 mg) doses suppressed T4 concentrations at 21 days of age. Testis weight was increased by 14.8% (LD) and 16.5% (HD) compared with controls. DSP was increased by 20.4% in the low dose and 25% in the high dose animals compared with controls. The number of Sertoli cells per testis was increased by 32.6 and 39.4% in low and high dose animals, respectively. A similar study in which the lactating females were only dosed twice per week (experiment 11) did not show any differences in these parameters. These results indicate that continuous exposure of lactating female rats to PCBs increases testis weight, sperm production and Sertoli cell numbers in the adult male offspring.

Aging↗
PubMed2001

Clinical significance of microvessel density in multiple myeloma patients.

To investigate the role of angiogenesis in multiple myeloma (MM), bone marrow biopsy from 75 adults with newly diagnosed, untreated MM were evaluated. Microvessels were scored in at least 3 areas ( x 200 fields) of the highest microvessel density in representative sections of each bone marrow specimen using immunohistochemistry for CD34. Prognostic variables were also evaluated for the overall survival. Microvessel counts were significantly higher in patients with MM (n=69.42+/-9.67), compared with control (n=26.81+/-2.85). Microvessel density had a weak correlation with percentage of bone marrow plasma cells. By univariate analysis, age, beta2-microglobulin, serum albumin, serum creatinine, serum calcium, hemoglobin, platelet count, and bone marrow plasma cell percentage were correlated with survival. By multivariate analysis, age, serum albumin, serum creatinine, hemoglobin, platelet count and bone marrow plasma cell percentage were correlated with overall survival, whereas microvessel density was not. In summary, microvessel density in bone marrow of MM is significantly increased compared to control, but was not correlated with overall survival. Further studies regarding angiogeneic molecules are needed to determine the functional role of angiogenesis in MM.

Adult↗
PubMed2001

Clinical impacts of tumor cell contamination of hematopoietic stem cell products in metastatic breast cancer patients undergoing autologous peripheral blood stem cell transplantation: multicenter trial.

To determine whether the tumor cell contamination of peripheral blood stem cells influences clinical impacts on high-dose chemotherapy in patients with metastatic breast cancer, we analyzed carcinoembryonic antigen (CEA) mRNA in the apheresis products by nested RT-PCR (reverse transcriptase-polymerase chain reaction). A total of 38 metastatic breast cancer patients and ten normal healthy subjects as a negative control were included. Twenty out of 38 (51.3%) apheresis products from patients with metastatic breast cancer were positive for CEA mRNA. CEA mRNA was noted in 54.8% (17/31) of patients mobilized with chemotherapy plus G-CSF and 42.8% (3/7) of patients with G-CSF alone. There was no significant difference in age, estrogen receptor, menopausal status, mobilization method, disease free interval, or number of metastasis sites (1 vs > or = 2) between positive and negative groups. The presence of CEA mRNA in apheresis products did not influence the time to progression and overall survival in both groups. However, both the univariate and the multivariate analysis disclosed that the number of metastasis was associated with survival significantly. We suggest that the tumor cell contamination does not predict poor treatment outcome in patients with metastatic breast cancer.

Adult↗
PubMed2001

Effects of smoking on the mortality of lung cancer in Korean men.

Few studies have examined the effects of smoking on the morbidity and mortality of lung cancer in Korean men. In Korea, where the prevalence of smoking is among the highest in the world, the morbidity and mortality of lung cancer are rapidly escalating. The objectives of this study were to prospectively examine the effects of smoking on lung cancer and to determine the combined effects of the amount, duration and age that smoking was started. The design was a prospective cohort study with a follow-up period of six years (1993-1998). The subjects included a total of 305,687 Korean men from 35 to 64 years of age who received health insurance from the Korea Medical Insurance Corporation and who had biennial medical evaluations in 1992. The main outcome measures were deaths from lung cancer. As a baseline, 58.2% were current cigarette smokers. Between 1993 and 1998, 891 lung cancer events (34.4/100,000 people per year) occurred. In multivariate Cox proportional hazards models controlling for age, exercise and alcohol use, current smoking increased the risk of lung cancer (risk ratio [RR], 5.6; 95% confidence interval [CI], 4.2 - 7.3). There were significant dose-response relationships to the amount, duration of smoking and age that smoking was started. Compared with nonsmokers, the RR from current smokers who smoked 20 cigarettes per day for over 30 years was 8.2 (5.9 - 11.3), the RR from current smokers who smoked for over 30 years and were less then 19 years of age when they started smoking was 7.8 (5.2 - 11.9), and the RR for those who smoke 20 cigarettes per day and were less than 19 years of age when they started smoking was 8.3 (5.9 -11.6). This study demonstrates that in Korea smoking is a major independent risk factor for lung cancer, and that the risk increases with an increased amount, longer duration, and younger starting age.

Adult↗
PubMed2001

Detection of malignant cells in pleural fluid or ascites by CD44v8-10/CD44v10 competitive RT-PCR.

BACKGROUND: CD44 is a cell surface adhesion molecule which has been implicated in various biologic functions as lymphocyte homing and activation, cellular migration and extracellular matrix adhesion. Over-expression of CD44v8-10 has been found in several cancers and is considered to be associated with tumor progression and metastasis. Recently, a novel molecular method, CD44v8-10/CD44v10 competitive reverse transcription-polymerase chain reaction(RT-PCR) has been developed for detecting cancer cells over-expressing CD44v8-10. METHODS: We analyzed from benign and malignant pleural effusion and ascites by CD44 competitive RT-PCR and compared to the conventional cytology. RESULTS: The CD44 competitive RT-PCR analysis showed that all the 24 samples associated with benign disease presented a predominant expression of the CD44v10 transcript (v8-10/v10 ratio: 0.126-0.948), whereas 6 of 7 malignant pleural samples associated with cytology positive cancer expressed the CD44v8-10 transcript (v8-10/v10 ratio > 1.00). CONCLUSION: These results indicate that CD44 competitive RT-PCR assay is a useful and adjunct to cytological examination in cancer diagnosis, especially in detecting exfoliated cancer cells in pleural effusion.

Adult↗
PubMed2001

Effect of heavy metals (Cu, Pb, and Ni) on the compositions of EPS in biofilms.

A series of batch adsorption tests to estimate the biofilm capacity for removal of the heavy metals (Cu, Pb, and Ni) in wastewater were carried out. The metal sorption results were fitted to the Freundlich isotherm model to compare their sorption capacity. The change of the composition of EPSs (extracellular polymeric substances) was simultaneously represented by the ratio of carbohydrate to protein (C/P) when the biofilm was exposed to the heavy metals. EPS composed of slime loosely bound to the cell and capsular materials was extracted by the four general extraction methods including regular centrifugation, regular centrifugation with formaldehyde, EDTA extraction and steam extraction. Although the various extraction methods showed different results, C/P ratio of biofilm exposed to copper and lead metal ions was generally lower than that of control.

Adsorption↗
PubMed2001

Mutational study of the role of tyrosine-49 in the Saccharomyces cerevisiae xylose reductase.

The xyl1 gene encoding xylose reductase was cloned from Saccharomyces cerevisiae and expressed in Escherichia coli. The purified enzyme readily carried out xylose reduction in vitro. It prefers NADPH as the co-enzyme by about 80-fold over NADH. Compared to the native enzyme purified from S. cerevisiae (Kuhn et al., 1995), the recombinant xylose reductase displayed slightly higher (about two-fold) affinities (K(m)) for the substrate (xylose) and co-factor (NADPH), as well as a 3.9-fold faster turnover number (K(cat)) and 7.4-fold greater catalytic efficiency (K(cat)/K(m)). The reason for the apparent discrepancies in kinetic constants between the recombinant and native S. cerevisiae xylose reductases is not known. Replacement of Tyr49 by Phe in the recombinant enzyme led to greater than 98% loss of activity, suggesting that this residue plays a critical role in catalysis. Intrinsic enzyme fluorescence spectroscopic analysis showed that the wild-type and the Y49F variant both bound the co-enzyme NADPH with similar affinity. This supports the view that Tyr49 is involved in interaction with the substrate and not the co-factor during catalysis.

Aldehyde Reductase↗
PubMed2000

Core-shell type polymeric nanoparticles composed of poly(L-lactic acid) and poly(N-isopropylacrylamide).

Poly(L-lactic acid)/poly(N-isopropylacrylamide) (abbreviated as LN) block copolymers were synthesized and the LN nanoparticles were prepared by simple diafiltration method. The thermal transition of the LN nanoparticles was at 32.3 degrees C, the lower critical solution temperature (LCST) of the polymer. The fluorescence spectroscopy data showed that LN was self-assembled in water to form core-shell structure nanoparticles, and the critical association concentration (CAC) value was estimated as 1.3x10(-2) g/l. From the transmission electron microscope observations, the LN nanoparticles were spherically shaped and ranged in size between 30 and 50 nm below the LCST. The hydrated size was measured by photon correlation spectroscopy, and reversible size changes were investigated by the factor of temperature. The release of indomethacin from the LN nanoparticles was thermo-sensitive due to the unique characteristic of poly(N-isopropylacrylamide).

Acrylic Resins↗
PubMed2000

Formation of fibrillar multimers of oat beta-glucosidase isoenzymes is mediated by the As-Glu1 monomer.

Oat beta-glucosidase (EC 3.2.1.21) exists in two isomeric forms of homomultimer (type I) and heteromultimer (type II), which are comprised of two 60 kDa monomers of As-Glu1 and As-Glu2. The cDNA of As-Glu2 was cloned in this study, whereas As-Glu1 was previously cloned as As-P60. The As-Glu2 cDNA encodes a plastid-directing transit peptide of 57 amino acid residues and a mature protein of 521 amino acid residues. The amino acid sequence of As-Glu2 is highly homologous to that of As-Glu1, except for their C-terminal portions. When the two cDNAs of the mature proteins were expressed as T7.Tag-fused proteins in Escherichia coli, they produced soluble and enzymatically active T7.Tag-As-Glu1 and T7.Tag-As-Glu2 proteins. The T7.Tag-As-Glu1 was assembled into a donut-shaped hexamer ring which was in turn stacked in integer numbers to form long fibrillar homomultimers of different lengths with a molecular mass of up to several million daltons. On the other hand, the T7.Tag-As-Glu2 primarily formed a dimer rather than a multimer. When both cDNAs of As-Glu1 and As-Glu2 were co-expressed as T7.Tag-fused mature proteins, they were also assembled into a hexamer ring comprised of the two monomers in a 1:1 stoichiometry. The heteromeric hexamer was stacked in smaller numbers to form the heteromultimer of T7. Tag-As-Glu1 and -As-Glu2. The results indicate that the As-Glu1 monomer plays a crucial role in the formation of both the As-Glu1 homomultimer and the As-Glu1 and As-Glu2 heteromultimer. We describe here a unique structure for the oat beta-glucosidase fibrillar multimer that is formed by stacking the hexamer rings composed of As-Glu1 and/or As-Glu2.

Amino Acid Sequence↗
PubMed2000

Identification of motifs for cell adhesion within the repeated domains of transforming growth factor-beta-induced gene, betaig-h3.

betaig-h3 is a transforming growth factor-beta-inducible cell adhesion molecule that has four characteristic homologous repeated domains. We made recombinant betaig-h3 proteins, which were highly active in mediating human corneal epithelial (HCE) cell adhesion and spreading. The 2nd and the 4th repeated domains were sufficient to mediate HCE cell adhesion. A sequence analysis showed that aspartic acid (Asp) and isoleucine (Ile) of the 2nd and the 4th domains are highly conserved in many fasciclin 1 homologous (fas-1) domains. Substitution mutational study identified these two amino acids are essential for cell adhesion. Synthetic peptides containing Asp and Ile, NKDIL and EPDIM derived from the 2nd and the 4th domains, respectively, almost completely blocked cell adhesion mediated by not only wild type betaig-h3 but also each of the 2nd and the 4th domains. These peptides alone were fully active in mediating cell adhesion. In addition, we demonstrated the functional receptor for betaig-h3 is alpha(3)beta(1) integrin. These results, therefore, establish the essential motifs within the 2nd and the 4th domains of betaig-h3, which interact with alpha(3)beta(1) integrin to mediate HCE cell adhesion to betaig-h3 and suggest that other proteins containing Asp-Ile in their fas-1 domains could possibly function as cell adhesion molecules.

Amino Acid Sequence↗