Biomedical subjects

Eun-Ki Kim

Publications and source records attributed to Eun-Ki Kim.

7 recordsLinked to original sources

PubMed2005

Selective cadmium accumulation using recombinant Escherichia coli.

Recombinant Escherichia coli JM109 (pZH3-5/pMT), harboring a manganese transport gene (mntA) and a metal-sequestering protein (metallothionein [MT]) gene, was cultivated to accumulate cadmium (Cd) in an aqueous phase. Isopropyl beta-D-thiogalactoside (IPTG)-induced cells showed rapid Cd(2+) ion accumulation (90% of maximum accumulation in 15 min) and had an accumulation six times higher than that of the control. Under optimum conditions, i.e., pH 7, 37 degrees C and 0.5 (OD600), 1.5 mM IPTG induction resulted in the accumulation of 21.5 micromol Cd/g dry cell. Storage at 37 degrees C for 24 h had no effect on the accumulation. Significantly, Cd was selectively accumulated in a solution containing an equal concentration of three other metals, resulting in more than 90% of the total accumulated metals being Cd. The accumulation of Cd was reduced by the presence of Mn2+ ion whereas no significant effect was observed with Cu2+, Zn2+ and Pb2+ ions. A chelator, EDTA, had no effect on the accumulation up to 100 mM. The bioaccumulation rate followed Michaelis-Menten kinetics (Vm=2.7 micromol Cd2+/min.g dry cell, Km=0.67 microM). The equilibrium isotherm showed a Langmuir isotherm. In the membrane reactor experiment, 1 mg/l Cd in an inlet solution decreased to 0.2 mg/l in the effluent, removing 80% of Cd, continuously. These results indicated the potentials of a genetically modified microorganism for the highly selective accumulation of Cd at a low concentration and the future application to the removal and recovery of Cd.

Bacterial Proteins↗

PubMed2004

Synergistic effect of sophorolipid and loess combination in harmful algal blooms mitigation.

The inhibition effect of sophorolipid and removal efficiency of loess on Cochlodinium polykrikoides and Alexandrium tamarense was investigated separately in the laboratory. Based on this, the combination of sophorolipid and loess for harmful algal bloom mitigation was proposed. Algal sedimentation tests in the laboratory and in the field revealed that the combination of sophorolipid and loess showed synergistic effects both on the removal efficiencies and on the mitigation cost. The concentration of 1 g/l loess and 5 mg/l sophorolipid was determined as the optimum ratio for C. polykrikoides mitigation. In the field test, the effective concentration of loess and sophorolipid in the combination group was reduced to 10% and 25%, respectively, compared to the non-combination group, and the cost decreased more than 60%. The combination of loess and sophorolipid was considered as a promising novel method in harmful algal bloom mitigation.

Animals↗

PubMed2004

Screening of surfactants for harmful algal blooms mitigation.

Screening experiments were conducted in order to find promising synthetic surfactants for harmful algal blooms (HABs) mitigation. The chemically synthesized surfactant cocamidopropyl betaine (CAPB) showed characteristics of relatively high inhibition efficiency, high biodegradability and low cost. The motility inhibition ratios of 10 mg/L CAPB on Cochlodinium polykrikoides and Alexandrium tamarense were about 60% after 5 min. The biodegradation test indicated that the half-life of CAPB in seawater was shorter than one day and 90% was biodegraded after five days under the initial concentration of 100 mg/L at 25 degrees C. Further cell lysis experiments revealed the selective lysis effect of CAPB on different HAB organisms. More than 90% of C. polykrikoides lysed at the concentration of 10 mg/L CAPB after 24 h and at 15 mg/L CAPB after 4 h, whereas the lysis effect of CAPB on A. tamarense was slight, no more than 10% after 2 h interaction with 50 mg/L CAPB. This research provided preliminary data for CAPB as a candidate in harmful algal blooms mitigation and pointed out unresolved problems for its practical application in the meantime.

Animals↗

PubMed2004

Cloning and characterization of the bovine testicular PH-20 hyaluronidase core domain.

The core nucleotide sequence of bovine (Bos taurus) testicular PH-20 hyaluronidase was cloned using one step RT-PCR. The 5' and 3' regions were cloned separately and a sequence overlap of 124 bp facilitated the fusion of these two fragments by overlapping PCR, resulting in a concatenated sequence of 1422 bp. This nucleotide sequence and its deduced amino acid sequence were compared to homologous sequences from eight other mammal species. The bovine sequences were most similar to those of the pig, Sus scrofa (swine Spam1: 79.1% nucleotide and 70.1% amino acid similarity) and least similar to sequences from the Norway rat, Rattus norvegicus (murine Spam1: 61% nucleotide and 53.3% amino acid similarity). A phylogenetic analysis joined the red fox (Vulpes vulpes) sequence as sister to the bull-pig pair. Twelve cysteine residues were conserved among all nine aligned amino acid sequences and five proposed glycosylation sites have been identified. The feasibility of developing an effective, low-cost bovine PH-20 expression system is discussed in light of these new data.

Amino Acid Sequence↗

PubMed2002

Inhibitory effect of zeatin, isolated from Fiatoua villosa, on acetylcholinesterase activity from PC12 cells.

Acetylcholinesterase (AChE) inhibitors, which enhance cholinergic transmission by reducing the enzymatic degradation of acetylcholine, are the only source of the compound that is currently approved for the treatment of Alzheimer's disease (AD). The methanol extract from Fiatoua villosa among 100 traditional edible plants that were tested, showed the most potent inhibitory effect (51%) on acetylcholinesterase in vitro. After the sequential solvent fractionation of the methanol extract of Fiatoua villosa, the active fraction was repeatedly subjected to open-column chromatography on silica gel. From the highest inhibitory fraction, the chloroform fraction (75%) on AChE, the single compound, was obtained by the Sep-Pak Cartridge (C18: reverse phase column). This compound was finally purified by HPLC (micro-bondapack C18 reverse phase column: 19 x 300 mm). According to the electron impact mass spectrometry (EI-MS), we confirmed that the molecular mass was 219 m/z. The structure of this compound was identified as zeatin [2-methyl-4-(1H-purine-6-ylamino)-2-buten-1-ol], one of the derivatives of purine adenine. The concentration that was required for 50% enzyme inhibition (IC50 value) was 1.09 x 10(-4) M. This study demonstrated that the zeatin from Fiatoua villosa appeared to be the most potent AChE inhibitor in AD.

Acetylcholinesterase↗

PubMed2002

Ursolic acid of Origanum majorana L. reduces Abeta-induced oxidative injury.

Amyloid beta protein (Abeta) increases free radical production and lipid peroxidation in PC12 nerve cells, leading to apoptosis and cell death. The effect of ursolic acid from Origanum majorana L. on Abeta-induced neurotoxicity was investigated using PC12 cells. Pretreatment with isolated ursolic acid and vitamin E prevented the PC12 cell from reactive oxygen species (ROS) toxicity that is mediated by Abeta. The ursolic acid resulted in decreased Abeta toxicity assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH), and trypan blue assay. Thus, treatment with these antioxidants inhibited the Abeta-induced neurotoxic effect. Therefore, these results indicate that micromolar Abeta-induced oxidative cell death is reduced by ursolic acid from Origanum majorana L.

Alzheimer Disease↗

PubMedDate not supplied

Antioxidative and anti-diabetic effects of amaranth (Amaranthus esculantus) in streptozotocin-induced diabetic rats.

The anti-diabetic and antioxidative effect of amaranth grain (AG) and its oil fraction (AO) was studied in streptozotocin-induced diabetic rats. Male Sprague-Dawley rats were divided into four groups after induction of STZ-diabetes: normal control; diabetic control; diabetic-AG supplement (500 g kg(-1) diet); diabetic-AO supplement (100 g kg(-1) diet) and fed experimental diets for 3 weeks. Serum glucose, insulin, activities of serum marker enzymes of liver function and liver cytosolic antioxidant enzymes were measured. The AG and AO supplement significantly decreased the serum glucose and increased serum insulin level in diabetic rats. Serum concentration of liver function marker enzymes, GOT and GPT, were also normalized by AG and AO treatment in diabetic rats. Liver cytosolic SOD and GSH-reductase activities were significantly increased, and catalase, peroxidase and GSH-Px activities were decreased in diabetic rats. AG and AO supplement reverted the antioxidant enzyme activities to near normal values. Hepatic lipid peroxide product was significantly higher, and GSH content was decreased in diabetic rats. However, AG and AO supplement normalized these values. Our data suggest that AG and AO supplement, as an antioxidant therapy, may be beneficial for correcting hyperglycaemia and preventing diabetic complications.

Amaranthus↗