Search PubMed⌕ Search

Biomedical subjects

J Kim

Publications and source records attributed to J Kim.

At least 1,081 records · Page 60Linked to original sources
PubMed1990

An ATP-modulated specific association of glyceraldehyde-3-phosphate dehydrogenase with human erythrocyte glucose transporter.

Glyceraldehyde-3-phosphate dehydrogenase was found to bind in vitro to purified, human erythrocyte glucose transporter reconstituted into vesicles. Mild tryptic digestion of the glucose transporter totally inactivated the binding, suggesting that the cytoplasmic domain of the transporter is involved in the binding to glyceraldehyde-3-phosphate dehydrogenase. The binding was abolished in the presence of antisera raised against the purified glucose transporter, further supporting specificity of this interaction. The binding was reversible with a dissociation constant (Kd) of 3.3 x 10(-6) M and a total capacity (Bt) of approximately 30 nmol/mg of protein indicating a stoichiometry of one enzyme-tetramer per accessible transporter. The binding was sensitive to changes in pH showing an optimum at around pH 7.0. KCl and NaCl inhibited the binding in a simple dose-dependent manner with Ki of 40 and 20 mM, respectively. The binding was also inhibited by NAD+ with an estimated Ki of 3 mM. ATP, on the other hand, enhanced the binding by up to 3-fold in a dose-dependent manner with an apparent Ka of approximately 6 mM. The binding was not affected by D-glucose or cytochalasin B. The binding did not affect either the glucose or cytochalasin B in binding affinities or the transport activity of the transporter. However, the enzyme was inactivated totally upon binding to the transporter. Based on these findings, we suggest that a significant portion of glyceraldehyde-3-phosphate dehydrogenase in human erythrocytes exists as an inactive form via an ATP-dependent, reversible association with glucose transporter, and that this association may exert regulatory intervention on nucleotide metabolism in vitro.

Adenosine Triphosphate↗
PubMed1990

Characterization of two types of fetal hemoglobin: alpha 2G gamma 2 and alpha 2A gamma 2.

The effect of differences in G gamma and A gamma fractions of fetal hemoglobin (HbF) on the kinetics of polymerization of HbS-HbF mixtures was studied. We also examined their effect on oxygen affinity, surface hydrophobicity, mechanical stability, and solubility of HbF. Differences in G gamma:A gamma ratio did not affect the polymerization of mixtures of HbF and HbS, suggesting that the inhibitory effect of HbF on the polymerization of HbS is independent of the G gamma:A gamma ratio of HbF and is totally dependent on the fraction of HbF in the mixture. The oxygen equilibrium curve of HbF was not affected by differences in the ratios of G gamma and A gamma in HbF. In contrast, surface hydrophobicity, mechanical stability, and solubility of HbF were affected by differences in the G gamma:A gamma ratio. The higher the G gamma:A gamma ratio, the smaller the elution volume on a TSK Gel SW hydrophobic column in high phosphate buffer. The mechanical stability of HbF was also dependent on the ratio of G gamma:A gamma; stability was greater at higher fractions of A gamma. Differences in the G gamma:A gamma ratio also affected solubility of HbF: HbF containing the higher fraction of G gamma was the more soluble. These data indicate that although alanine at the 136th position of the gamma chains has a stronger surface hydrophobicity than does glycine, this difference does not affect either the polymerization of HbS or the oxygen affinity of HbF.

Alanine↗
PubMed1990

Mammalian mitochondrial endonuclease activities specific for ultraviolet-irradiated DNA.

Mitochondrial forms of uracil DNA glycosylase and UV endonuclease have been purified and characterized from the mouse plasmacytoma cell line, MPC-11. As in other cell types, the mitochondrial uracil DNA glycosylase has properties very similar to those of the nuclear enzyme, although in this case the mitochondrial activity was also distinguishable by extreme sensitivity to dilution. Three mitochondrial UV endonuclease activities are also similar to nuclear enzymes; however, the relative amounts of these enzyme activities in the mitochondria is significantly different from that in the nucleus. In particular, mitochondria contain a much higher proportion of an activity analogous to UV endonuclease III. Nuclear UV endonuclease III activity is absent from XP group D fibroblasts and XP group D lymphoblasts have reduced, but detectable levels of the mitochondrial form of this enzyme. This residual activity differs in its properties from the normal mitochondrial form of UV endonuclease III, however. The presence of these enzyme activities which function in base excision repair suggests that such DNA repair occurs in mitochondria. Alternatively, these enzymes might act to mark damaged mitochondrial genomes for subsequent degradation.

Animals↗
PubMed1990

Colorimetric changes in composites resulting from visible-light-initiated polymerization.

We evaluated three shades of nine light-cured composites to determine the colorimetric changes which occur as a result of the photo-polymerization reaction. A photo-electric tristimulus colorimeter was used to measure the color of a 0.5-mm-thick sample of composite on two different backgrounds before and after the polymerization process had been initiated. The results showed that each of the photo-initiated composites tested produced a visually significant change in color as a result of the polymerization reaction, regardless of the shade of the backing. In general, the light-cured composites produced a characteristic chromatic shift toward the blue region of color space, which resulted in a perceived decrease in yellow chroma. Therefore, direct shade selection of a resin composite which is more yellow or more chromatic than the tooth which is being restored is recommended to compensate for this characteristic immediate color shift.

Color↗
PubMed1990

kem mutations affect nuclear fusion in Saccharomyces cerevisiae.

We have identified mutations in three genes of Saccharomyces cerevisiae, KEM1, KEM2 and KEM3, that enhance the nuclear fusion defect of kar1-1 yeast during conjugation. The KEM1 and KEM3 genes are located on the left arm of chromosome VII. Kem mutations reduce nuclear fusion whether the kem and the kar1-1 mutations are in the same or in different parents (i.e., in both kem kar1-1 X wild-type and kem X kar 1-1 crosses). kem 1 X kem 1 crosses show a defect in nuclear fusion, but kem 1 X wild-type crosses do not. Mutant kem 1 strains are hypersensitive to benomyl, lose chromosomes at a rate 10-20-fold higher than KEM+ strains, and lose viability upon nitrogen starvation. In addition, kem 1/kem 1 diploids are unable to sporulate. Cells containing a kem 1 null allele grow very poorly, have an elongated rod-shape and are defective in spindle pole body duplication and/or separation. The KEM 1 gene, which is expressed as a 5.5-kb mRNA transcript, contains a 4.6-kb open reading frame encoding a 175-kD protein.

Amino Acid Sequence↗
PubMed1990

Effects of heat-, CaCl2- and ethanol-treatments on activation of Bacillus spores.

The effects of heat, CaCl2, and ethanol on activation of Bacillus spores were determined by monitoring the absorbance decrease during germination in inosine. Bacillus cereus T, B. subtilis A and B. megaterium QM B1551 spores were activated by heat- and CaCl2-treatments. Ethanol activated B. megaterium and B. subtilis spores yet did not activate B. cereus spores. CaCl2- and ethanol-activations were less effective than heat-activation as judged by optimal germination rates and germination extents. The presence of CaCl2 during heat-treatment inhibited heat-activation of all three Bacillus spores without affecting viability or dipicolinic acid content of the spores. The electrophoretic patterns of coat plus outer membrane proteins extracted from Bacillus spores treated with CaCl2 and heat in the presence of CaCl2 were similar to each other and were distinctively different from the patterns of proteins from unactivated spores or the spores treated with heat and/or ethanol.

Bacillus↗
PubMed1990

Ultrastructural localization of carbonic anhydrase II in subpopulations of intercalated cells of the rat kidney.

At least two configurations of intercalated cells, type A and type B, are present in the cortical collecting duct. Intercalated cells are rich in carbonic anhydrase. However, it is not known whether there are differences in the level and subcellular distribution of this enzyme between type A and type B intercalated cells. The purpose of this study was to determine the relative content and intracellular distribution of carbonic anhydrase II in the various subpopulations of intercalated cells in the rat collecting duct. A rabbit polyclonal antibody directed against mouse erythrocyte carbonic anhydrase II was employed to localize carbonic anhydrase, II by light and electron microscopy by an indirect immunoperoxidase method. A Western immunoblot analysis of homogenates of rat kidney cortex and medulla with the carbonic anhydrase II antibody revealed a single polypeptide band at 29 kDa corresponding to the molecular size of carbonic anhydrase II. By both light and electron microscopy, carbonic anhydrase II immunoreactivity was present in all intercalated cells but the intensity of staining was much greater in type A than in type B cells. In addition, immunostaining in type A cells was especially pronounced in the apical cytoplasm and apical microprojections whereas in type B cells, immunostaining was more diffuse throughout the cytoplasm. A third configuration of intercalated cell with diffuse immunostaining for carbonic anhydrase II was occasionally observed in the connecting segment. Very weak immunostaining was present in principal cells, whereas connecting tubule cells and inner medullary collecting duct cells were negative for carbonic anhydrase II.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Postoperative radiotherapy for stage IB carcinoma of the uterine cervix.

Sixty patients, treated with postoperative radiation therapy following radical hysterectomy and pelvic lymphadenectomy for stage lb carcinoma of the uterine cervix between Jan. 1980 and Dec. 1984 at Department of Radiation Oncology, Yonsei University College of Medicine, were retrospectively analysed. The minimum follow-up period was 5 years. The indications for postoperative radiotherapy were positive pelvic lymph node (34 pts), a large tumor size more than 3 cm in longest diameter (18 pts), positive surgical margin (10 pts), deep stromal invasion (10 pts), and lymphatic permeation (9 pts). The overall 5-year survival rate was 81.8%. The univariate analysis of prognostic factors disclosed tumor size (less than 3cm, greater than or equal to 3cm) and the status of the surgical margin (positive, negative) as significant factors (tumor size; 88.1% vs 6.3%, surgical margin; 85.5% vs 60%, p less than 0.05). Age (less than or equal to 40, greater than 40 yrs) was marginally significant (90.2% vs 73.1%, p less than 0.1). Multivariate analysis clarified two independent prognostic factors; tumor size (p = 0.010) and surgical margin (p = 0.004). Analysis of the tumor factors with the radiation dose disclosed a better survival rate for patients with a positive surgical margin who were given over 50 Gy than for those who were given below 50 Gy in patients (4/4, 100% vs 2/6, 33.4%; p = 0.06). Significant complications requiring surgical correction were not observed. In conclusion, it is believed that the status of the surgical margin and tumor size both have important prognostic significance, and that a radiation dose over 50 Gy is advisable for patients with a positive surgical margin.

Adult↗
PubMed1990

Influence of caffeine on the induction of SOS functions recA and umuC by mitomycin C in Escherichia coli.

Caffeine alone induced the SOS functions recA and umuC in wild type recA-lacZ and umuC-lacZ fusion systems in Escherichia coli strains. Caffeine was also able to induce umuC in a umuC-lacZ fusion strain defective in excision repair. Caffeine however was unable to significantly induce recA in a recA-lacZ fusion strain defective in excision repair. Mitomycin C (MMC) at a concentration of 0.5 microgram/ml functioned as a stronger inducer of recA and umuC than caffeine at 2 mg/ml. Cell growth in the presence of both caffeine (2 mg/ml) and MMC (0.05, 0.1 and 0.5 microgram/ml) resulted in primarily an additive induction of recA and umuC.

Alkylating Agents↗
PubMed1990

Fusion of Madin-Darby canine kidney cells by HVJ (Sendai virus): absence of direct association of virus particles with the site of membrane fusion.

The process of cell fusion of Madin-Darby canine kidney (MDCK) cells by HVJ (Sendai virus) was investigated to determine whether the HVJ particles were directly associated with the site of membrane fusion. Confluent monolayer cultures of MDCK cells are sealed together by tight junctions on the apices of their lateral membranes, so added virus particles can be adsorbed only to the apical surfaces of the cells. After incubation with HVJ at 37 degrees C for 30 min, the cells still appeared mononucleate and unfused by light microscopy, but electron microscopic examination showed that fusion at the lateral membranes had occurred below the tight junctions. Furthermore, when fluorescein isothiocyanate (FITC)-labeled macromolecules, which cannot pass across the gap junctions, were injected into the cells at this stage, labeled macromolecules were found to diffuse into the adjacent cells. These findings strongly suggest that cell fusion was initiated in the lateral membrane, a region distinct from the site of adsorbed HVJ particles. Thus, the virus particles were not directly associated with the fusion site, but induced fusion of the lateral membranes indirectly.

Animals↗