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Biomedical subjects

H Rhee

Publications and source records attributed to H Rhee.

At least 37 records · Page 2Linked to original sources
PubMed1989

2-Oxoaldehyde metabolism in microorganisms.

The properties of methylglyoxal-metabolizing enzymes in prokaryotic and eukaryotic microorganisms were studied systematically and compared with those of mammalian enzymes. The enzymes constitute a glycolytic bypass and convert methylglyoxal into pyruvate via lactate. The first step in this conversion is catalyzed by glyoxalase I, methylglyoxal reductase, or methylglyoxal dehydrogenase. The regulation of the yeast glyoxalase system was analyzed. The system was closely related to the proliferative states of yeast cells, the activity of the system being high in dividing cells and low in nondividing ones. The gene for the glyoxalase I of Pseudomonas putida and the genes responsible for the activity of glyoxalase I and methylglyoxal reductase in Saccharomyces cerevisiae were cloned and their structural and phenotypic characters studied.

Alcohol Oxidoreductases↗
PubMed1988

Metabolism of 2-oxoaldehyde in mold. Purification and characterization of two methylglyoxal reductases from Aspergillus niger.

Two kinds of methylglyoxal reductases were purified to apparent homogeneity from Aspergillus niger and designated MGR I and MGR II. Both enzymes consisted of a single polypeptide chain with a relative molecular mass of 36,000 (MGR I) and 38,000 (MGR II). NADPH was specifically required for the activities of both enzymes and Km values for NADPH were 54 microM (MGR I) and 6.8 microM (MGR II). MGR I was specific to 2-oxoaldehydes [glyoxal, methylglyoxal (Km = 15.4 mM) and phenylglyoxal], whereas MGR II was active on both 2-oxoaldehydes [glyoxal (Km = 10 mM), methylglyoxal (Km = 1.43 mM), phenylglyoxal (Km = 4.35 mM) and 4,5-dioxovalerate] and some aldehydes (propionaldehyde and acetaldehyde). Optimal pH values for MGR I and MGR II activities were 9.0 and 6.5 respectively. Both enzymes were inactivated by a brief incubation with 2-oxoaldehydes (glyoxal, methylglyoxal and phenylglyoxal) in the absence of NADPH. MGR I activity was competitively inhibited by NADP+ and the Ki value for NADP+ was calculated to be 0.49 mM. On the other hand, the inhibition of MGR II activity by NADP+ was of mixed type, the Ki value for NADP+ being 45 microM. MGR I was different from MGR II in amino acid composition.

Alcohol Oxidoreductases↗
PubMed1988

L-alanine: 4,5-dioxovalerate aminotransferase from Pseudomonas riboflavina: purification and inactivation by methylglyoxal.

L-Alanine:4,5-dioxovalerate aminotransferase, which catalyzes transamination between L-alanine and 4,5-dioxovalerate to yield delta-aminolevulinate and pyruvate, has been purified from Pseudomonas riboflavina IFO 3140. The enzyme had a molecular weight of 190,000 and consisted of four identical subunits. It was crystallized as pale yellow needles. The enzyme used L-alanine (relative activity 100), beta-alanine (39), and L-ornithine (14) as amino donors. gamma-aminobutyrate (55) and epsilon-aminocaproate (34) were also effective as amino donors. The reaction proceeded according to a ping-pong mechanism and the Km values for L-alanine and 4,5-dioxovalerate were 1.7 and 0.75 mM, respectively. The activity of the enzyme is strongly inhibited by pyruvate, hemin, and methylglyoxal. Methylglyoxal interacted with the enzyme and brought about a complete inactivation.

Aldehydes↗
PubMed1987

Molecular cloning of the Pseudomonas putida glyoxalase I gene in Escherichia coli.

The glyoxalase I gene of Pseudomonas putida was cloned onto a vector plasmid pBR 322 as a 7.5 kilobase Sau 3AI fragment of chromosomal DNA and the hybrid plasmid was designated pGI 318. The gene responsible for the glyoxalase I activity in pGI 318 was recloned in pBR 322 as a 2.2 kilobase Hin dIII fragment and was designated pGI 423. The P. putida glyoxalase I gene on pGI 318 and pGI 423 was highly expressed in E. coli cells and the glyoxalase I activity level was increased more than 150 fold in the pGI 423 bearing strain compared with that of E. coli cells without pGI 423. The E. coli transformants harboring pGI 318 or pGI 423 could grow normally in the presence of methylglyoxal, although the E. coli cells without plasmid were inhibited to grow and showed the extremely elongated cell shape.

Cell Division↗
PubMed1987

Metabolism of 2-ketoaldehydes in mold: purification and characterization of glyoxalase I from Aspergillus niger.

Glyoxalase I catalyzing the conversion of methylglyoxal into S-lactoylglutathione in the presence of glutathione was purified approximately 1,400-fold with 2.9% activity yield from mold, Aspergillus niger. The enzyme consisted of a single polypeptide chain with a relative molecular weight of 36,000 on both SDS-polyacrylamide gel electrophoresis and Sephadex G-150 gel filtration. The enzyme was most active at pH 7.0, 35-37 degrees C. Among the various aldehydes tested, the enzyme was active on methylglyoxal and 4,5-dioxovalerate with Km values of 1.25 and 0.87 mM, respectively. The activity of the enzyme was completely inhibited by Zn2+ at 0.5 mM. An equimolar amount of EDTA (0.5 mM) protected the enzyme from inactivation by Zn2+. EDTA competitively (K1 = 1.3 mM) inhibited the activity of the enzyme. Fe2+ was a potent activator for the enzyme, the activation being approximately 2.4-fold at 0.5 mM.

Aldehydes↗
PubMed1987

The nationwide epidemiological study of mental disorders in korea.

The lifetime prevalences of DSM-III mental disorders using Korean version of DIS-III are presented. They were studied in 5,100 adults (aged 18 to 65) in household selected by two stage cluster sampling. Comparisons were made between regions, sex and age groups. International comparison with Epidemiologic Catchment Area program was also made.

Adolescent↗
PubMed1986

Purification and characterization of glyoxalase I from Pseudomonas putida.

Glyoxalase I was purified to apparent homogeneity from Pseudomonas putida. The enzyme was a monomer with a molecular weight of 20,000. The enzyme was most active at pH 8.0. The Km values for methylglyoxal and 4,5-dioxovale-rate are 3.5 mM and 1.2 mM, respectively. Contrary to the case of eukaryotic enzymes, chelating agents showed little inhibitory effects on the enzyme activity. Among the metal ions tested, Zn++ specifically and completely inhibited the activity of the enzyme at a millimolar level. The properties of bacterial glyoxalase I were quite different from mammalian and yeast enzymes.

Edetic Acid↗
PubMed1984

Effects of myocardial ischemia on cardiac contractility and ion transport in working and Langendorff rabbit heart.

In order to define the ischemic myocardial injury in terms of the possible alteration of cardiac membrane properties, Rb+ uptake and 3H-ouabain binding to cardiac tissue were compared in normal and ischemic rabbit hearts. In isolated Langendorff or working rabbit hearts, a global ischemia was produced by reducing the coronary flow of oxygenated Krebs-Henseleit solution for various time intervals. The normal or ischemic tissues were subjected to study the uptake of Rb+ and ouabain bindings. In Langendorff hearts there was little or no significant difference in active uptake of Rb+ in normal and ischemic heart. However, in the working heart, there was a significant decrease in Rb+ uptake in the ischemic hearts. As the case of Rb+ uptake ouabain binding was significantly reduced in ischemic working heart in comparison to working normal heart preparations at high concentrations of ouabain, the present study suggests the importance of cardiac contractility for the cellular energy metabolism and membrane transport activity.

Animals↗
PubMed1984

Analysis of phospho- and phosphonosphingolipids by high-performance liquid chromatography.

A simple and efficient method for the separation of phosphosphingolipids including phosphonosphingolipids by high-performance liquid chromatography is described. A mixture of authentic lipids consisting of sphingomyelin, ceramide phosphorylethanolamine, ceramide 2-aminoethylphosphonate, and ceramide N-methylaminoethylphosphonate was completely separated using a silica gel (Zorbax SIL) column with acetonitrile-methanol-water 72:40:10 (v/v) as eluting solvent. The elution of these sphingolipids was monitored directly with an ultraviolet spectromonitor at 207 nm. The practical limit of detection of each sphingolipid was about 0.2 microgram or 0.3 nmol. Using this method, we found that from one to four different phosphono- and/or phosphosphingolipids in fresh-water shellfish can be routinely identified and reproducibly quantified.

Animals↗
PubMed1984

Rapid progression of an aortic lesion in a patient with aortitis syndrome.

In a 28-year-old woman with aortitis syndrome, repeated aortography revealed the development of a coarctation of the abdominal aorta occurring over a period of 1 year. Clinical and surgical examinations showed evidence of inflammation and ruled out other diseases during that time. This suggests that in cases of aortitis syndrome arterial lesions may show rapid progression over short time periods and in the absence of untoward events.

Adult↗
PubMed1983

Evaluation of cytologic techniques for diagnosis of prostate cancer.

Two hundred forty-eight male patients seen on a urology service were diagnostically screened using four different cytologic tests for cancer of the prostate. The tests included voided urine cytology, prostate massage cytology, aspiration cytology, and postmassage urine cytology. The aspiration cytology was the most efficient screening test for the diagnosis of prostate malignancy.

Aged↗
PubMed1980

Screening tests for detection of bladder cancer.

Eighty-one individuals had urine cytologic studies, urinary carcinoembryonic antigen (CEA) determinations, and urinary immunoglobulin levels performed to evaluate various screening tests for the diagnosis of bladder cancer. Urinary cytologic studies detect the presence of bladder malignancy, and while false positive tests were troublesome, remain the primary screening test for bladder cancer. Urinary CEA was of little value in detecting vesical malignancy. Urinary immunoglobulins, particularly IGG and IGA, were significantly elevated in the presence of bladder cancer.

Carcinoembryonic Antigen↗