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Biomedical subjects

S R Kim

Publications and source records attributed to S R Kim.

At least 91 records · Page 5Linked to original sources
PubMed1997

Cloning of a human homolog of the yeast OGG1 gene that is involved in the repair of oxidative DNA damage.

We report the cloning of a human homolog of the yeast OGGC1 gene, which encodes a DNA glycosylase that excises an oxidatively damaged form of guanine, 8-hydroxyguanine (also known as 7,8-dihydro-8-oxoguanine). Since the deduced amino acid sequence (68 amino acids) of a human expressed sequence tag, N55394, matched a short stretch of yeast OGG1 protein with greater than 40% amino acid identity, a full length cDNA clone was isolated from a HeLa cell cDNA library with the N55394 clone as a probe. The cDNA clone encodes a predicted protein of 345 amino acids which is homologous to yeast OGG1 protein throughout the entire polypeptide sequence and shares 38% amino acid identity with yeast OGG1 protein. Moreover, we found that both a human homolog and yeast OGG1 protein possess two distinct DNA binding motifs, a helix-hairpin-helix (HhH) motif and a C2H2 zinc finger like motif, and a domain homologous to human and E. coli MutY proteins. Expression of a human homolog suppressed spontaneous mutagenesis of an E. coli (mutM mutY) mutant as in the case of yeast OGG1 protein. The gene was ubiquitously expressed in a variety of human organs and mapped to chromosome 3p26.2. These results strongly suggest that the gene isolated here is a human counterpart of the yeast OGGI gene and is involved in the repair of oxidative DNA damage in human cells.

Amino Acid Sequence↗
PubMed1997

Sleep pattern changes in menstrual cycles of women with premenstrual syndrome: a preliminary study.

OBJECTIVE: The objective of this study was to investigate the sleep pattern changes across the menstrual cycle in patients with premenstrual syndrome. STUDY DESIGN: This prospective study was conducted in a university-based premenstrual syndrome clinic. The patients were selected on the basis of the comprehensive interview and visual linear analog scale. Well-matched control subjects were also selected. All the subjects underwent two consecutive sleep pattern recordings during each of three different menstrual phases in 1 month. Nine sleep parameters were recorded. RESULTS: Three patients and six controls completed the study. No cycle-related fluctuation in any parameter was noted in either the patients or the controls. No significant differences in sleep pattern were noted in the patients when compared with the controls during the same phase of the menstrual cycle. CONCLUSION: Abnormal sleep pattern in relation to premenstrual syndrome or phases of the menstrual cycle was not demonstrated in this preliminary study.

Adult↗
PubMed1997

A case of pseudolymphoma of the liver with chronic hepatitis C.

A case of pseudolymphoma (reactive lymphoid hyperplasia) of the liver in a 72-year-old male with chronic hepatitis C is presented. Imaging studies, comprising ultrasonography, computed tomography, incremental computed tomography, and magnetic resonance imaging, suggested hepatocellular carcinoma. A tumor-like lesion was therefore resected. Grossly, the lesion was relatively poorly defined and measured 15 x 17 mm; microscopically, it consisted of lymphocytic proliferations forming follicles comprising numerous germinal centers that were mainly composed of L-26 positive B-cell lymphocytes. The lymphocytes surrounding germinal centers were mainly UCHL-1 positive T lymphocytes. The B cells in the lymphoid follicles stained positive for both kappa and lambda light chains at sequential frequencies, indicating polyclonal and benign features. These findings suggest that the diagnosis of pseudolymphoma of the liver is tenable from imaging studies supplemented, when necessary, with biopsy. Further studies may provide insights into diagnostic strategies and the mechanism of stimulation in HCV infections.

Aged↗
PubMed1997

The plasmid R64 thin pilus identified as a type IV pilus.

The entire nucleotide sequence of the pil region of the IncI1 plasmid R64 was determined. Analysis of the sequence indicated that 14 genes, designated pilI through pilV, are involved in the formation of the R64 thin pilus. Protein products of eight pil genes were identified by the maxicell procedure. The pilN product was shown to be a lipoprotein by an experiment using globomycin. A computer search revealed that several R64 pil genes have amino acid sequence homology with proteins involved in type IV pilus biogenesis, protein secretion, and transformation competence. The pilS and pilV products were suggested to be prepilins for the R64 thin pilus, and the pilU product appears to be a prepilin peptidase. These results suggest that the R64 thin pilus belongs to the type IV family, specifically group IVB, of pili. The requirement of the pilR and pilU genes for R64 liquid mating was demonstrated by constructing their frameshift mutations. Comparison of three type IVB pilus biogenesis systems, the pil system of R64, the toxin-coregulated pilus (tcp) system of Vibrio cholerae, and the bundle-forming pilus (bfp) system of enteropathogenic Escherichia coli, suggests that they have evolved from a common ancestral gene system.

Amino Acid Sequence↗
PubMed1996

PLC gamma 1 Src homology domain induces mitogenesis in quiescent NIH 3T3 fibroblasts.

Previously, we demonstrated that microinjection of phosphoinositide-specific phospholipase C gamma 1 (PLC gamma 1) and lipase-defective mutants of PLC gamma 1 induced G(0) growth arrested NIH 3T3 fibroblasts to enter S phase of the cell cycle. These experiments suggested that regions other than the catalytic domain of PLC gamma 1 may be responsible for inducing mitogenesis. To test other regions of PLC gamma 1 for DNA synthesis inducing activity, cDNA fragments encoding Src homology (SH) and pleckstrin homology (PH) domains were subcloned into the bacterial expression plasmid pGEX-2TK, and the GST fusion proteins were purified. The complete PLC gamma l SH domain peptide was found to induce DNA synthesis after microinjection into growth arrested fibroblasts. Peptides containing a single SH3 domain or two SH2 domains induced a partial response that was restored to full activity if they were co-injected. The PH domain peptide did not induce DNA synthesis. Thus, both SH3 and SH2 activity combine to give maximum DNA synthesis induction, demonstrating that non-catalytic structural domains of PLC gamma 1 have pronounced effects on mitogenic signaling pathways.

3T3 Cells↗
PubMed1996

Oviductal protein produces fluorescence staining of the perivitelline space in mouse oocytes.

Mouse oocytes were previously observed to undergo structural changes involving the perivitelline space (PVS) within the oviduct following ovulation, as visualized by staining with fluorochrome-protein conjugates. In the present study, this phenomenon was investigated in detail to determine the role of the oviduct and oocyte. Mouse ovarian oocytes matured in vitro were further incubated in medium or within explanted oviducts in vitro for varying periods of time and then stained with fluorescein isothiocyanate (FITC)-casein. Twenty percent of oocytes incubated within explanted oviducts for 3 hr showed distinct fluorescence staining of the PVS, whereas after 20 hr incubation, most (89%) oocytes were similarly stained. In contrast, no ovarian oocytes was stained when incubated in medium alone. Puromycin treatment during incubation of oocytes within explanted oviducts produced a dose-dependent decrease in the percentage of oocyte exhibiting PVS staining after FITC-casein exposure. FITC-casein staining of the PVS also occurred in all oocytes following incubation of in vitro-matured oocytes with oviductal tissue extract. In contrast, no oocytes incubated with serum exhibited fluorescence staining. Additionally, the PVS of oocytes failed to stain after incubation with either 0.001% of trypsin- or heat-treated oviductal homogenate. When zona pellucida (ZP) ghosts, devoid of ooplasm, were incubated within explanted oviducts, their PVS was stained brightly following FITC-casein treatment. From these results, it is concluded that proteinaceous material(s) secreted by the mouse oviduct is responsible for the fluorescence staining of the PVS of mouse oocytes and of ghost ZP. The ooplasm does not appear to play any role in altering the properties of the PVS staining.

Animals↗
PubMed1995

Prospective study of chemoprevention of hepatocellular carcinoma with Sho-saiko-to (TJ-9).

BACKGROUND: Most hepatocellular carcinomas (HCC) arise in patients with cirrhosis, in whom its incidence is high. The prevention of HCC in patients with cirrhosis is important. METHODS: A prospective, randomized, nonblind controlled study was performed to evaluate the preventive effect of Sho-saiko-to (TJ-9) on HCC development. TJ-9 is a Chinese herbal medicine that contains crude extracts of seven herbs; it has antitumor effects in experimental animals. Two hundred sixty patients with cirrhosis were randomly assigned to two groups, matched for age, sex, presence of hepatitis B surface antigen, and the severity of liver damage. The patients in the trial group were given TJ-9 at a daily oral dose of 7.5 g in addition to the conventional drugs given to the control patients. The patients were prospectively monitored for 60 months and the cumulative incidence of HCC and the survival rate in the two groups were calculated. RESULTS: The cumulative incidence curve for 5 years of the trial group was lower than that of the control group (P = 0.071). For the patients without HBs antigen, the difference was significant (P = 0.024). The survival curve for 5 years of the trial group was higher than that of the control group (P = 0.053). For the patients without HBs antigen, the difference was significant (P = 0.043). CONCLUSIONS: TJ-9 helped to prevent the development of HCC in patients with cirrhosis, particularly in patients without HBs antigen.

Adult↗
PubMed1995

Mating variation by DNA inversions of shufflon in plasmid R64.

Gene organization of the 54-kb transfer region of IncI1 plasmid R64 was deduced from the DNA sequence. Forty-eight ORFs were found in this region. A unique DNA rearrangement designated shufflon is located at the downstream region of an operon responsible for synthesis of thin pilus. The shufflon of R64 consists of four DNA segments, designated as A, B, C, and D, which are flanked and separated by seven 19-bp repeat sequences. Site-specific recombination mediated by the product of the rci gene between any two inverted repeats results in a complex DNA rearrangement. An analysis of open reading frames revealed that the shufflon is a biological switch to select one of seven C-terminal segments of the pilV genes. The products of pilV genes were shown to be components of thin pilus which was required for liquid mating. Seven R64 derivatives where the pilV genes were fixed in the seven C-terminal segments were constructed and their transfer frequencies in liquid mating were measured using various bacterial strains as recipients. Transfer frequencies of R64 in liquid mating strongly depended on the combination of C-terminal segments of the pilV genes in donor cells and bacterial strains of recipient cells, suggesting that the shufflon determines the recipient specificity in liquid mating of plasmid R64.

Biophysical Phenomena↗
PubMed1995

Leukaemia inhibitory factor in human endometrium during the menstrual cycle: cellular origin and action on production of glandular epithelial cell prostaglandin in vitro.

Leukaemia inhibitory factor (LIF) is a pleiotrophic cytokine which plays an obligatory role in mouse implantation. To investigate its potential role in the regulation of uterine function in the human, LIF secretion by isolated human endometrial glandular epithelial and stromal cells in primary culture was determined. Endometrial cells secreted a detectable amount of LIF protein during the first 48 h of culture. In the follicular and late-luteal phases, LIF secretion by both cell types was low. At every stage of the menstrual cycle, the epithelial cells secreted significantly more LIF than did stromal cells. Glandular epithelial cells of the mid-luteal phase, at the expected time of implantation in the human, secreted significantly more LIF than at other stages of the cycle. Stromal cells showed a similar, but nonsignificant, LIF secretion pattern. It could be concluded that endometrial LIF expression was dependent on cell type and stage of the menstrual cycle, and might thus play a role in human implantation. Oestradiol-17 beta stimulated both prostaglandin (PG) F and E release by the epithelial cells in both follicular and luteal phases. PGE release during the luteal phase was greater than in the follicular phase. However, addition of recombinant human LIF did not change either PGF or PGE release in either follicular or luteal phases, in the presence or absence of oestradiol.

Adult↗
PubMed1994

DNA rearrangement of the shufflon determines recipient specificity in liquid mating of IncI1 plasmid R64.

The shufflon is a unique DNA rearrangement found in plasmid R64. R64 shufflon consists of four DNA segments, which are flanked and separated by seven 19-bp repeat sequences. Site-specific recombination between any inverted repeats results in a complex DNA rearrangement where four DNA segments invert independently or in groups. The shufflon is a biological switch to select one of the seven C-terminal segments of the pilV gene. To examine the biological significance of the shufflon, R64 derivatives, where the pilV gene was fixed in seven C-terminal segments, were constructed and used as donor cells for liquid mating. The transfer frequencies depended markedly on the combinations of recipient bacterial strains and C-terminal segments of the pilV gene in donor cells, indicating that the shufflon determines the recipient specificity in liquid mating of R64. The products of the pilV genes were found to be a component of thin pili produced by R64.

Conjugation, Genetic↗
PubMed1994

Early flowering and reduced apical dominance result from ectopic expression of a rice MADS box gene.

Recent studies with dicot plants reveal that floral organ development is controlled by a group of regulatory factors containing the MADS domain. In this study, we have isolated and characterized a cDNA clone from rice, OsMADS1, which encodes a MADS-domain-containing protein. The OsMADS1 amino acid sequence shows 56.2% identity to AGL2 and 44.4% identity to AP1. The MADS box region was the most homologous to other MADS-domain-containing proteins. Northern blot analysis indicated that the rice MADS gene was preferentially expressed in floral organs. In situ localization studies showed that the transcript was uniformly present in young flower primordia and later became localized in palea, lemma, and ovary. Ectopic expression of OsMAD1 with the CaMV 35S promoter in transgenic tobacco plants dramatically alters development, resulting in short, bushy, early-flowering plants with reduced apical dominance. These results suggest that the OsMADS1 gene is involved in flower induction and that it may be used for genetic manipulation of certain plant species.

Amino Acid Sequence↗
PubMed1994

Developmental and environmental regulation of two ribosomal protein genes in tobacco.

Two cDNA clones, TSC29 and TSC40, were isolated from a cDNA library prepared from three-day-old tobacco cell suspension grown to early exponential stage. DNA sequence analyses and database searches revealed that the TSC29 transcript encodes a protein which is highly homologous to eukaryotic 60S ribosomal (r)-protein L25 and that the TSC40 product is homologous to rat 60S r-protein L34. Southern blot analysis showed that the putative r-protein genes are members of multigene families. Transcript levels of both genes were most abundant in three-day-old cell suspension and declined in older cultures. Transcripts were also present in plant vegetative and reproductive organs. However, for TSC40 in particular, the mRNA levels were lower in plant organs than in three-day-old cell suspension. Stems and roots exhibited higher expression than leaves and flowers, indicating that these clones are differentially regulated in various cell types. Both genes were expressed at low levels in mature seeds but transcript levels significantly increased after one day of germination, remained at a high level until day 4, and declined after day 5. In situ localization experiments with germinating seedlings revealed that the TSC29 transcript was preferentially localized in root tips, epidermis, and endosperm. Wounding increased the steady-state mRNA amounts of these r-protein genes, and 2,4-dichlorophenoxyacetic acid and benzyladenine further increased the transcript level.

Amino Acid Sequence↗
PubMed1993

Molecular cloning and characterization of anther-preferential cDNA encoding a putative actin-depolymerizing factor.

A cDNA clone, LMP131A, which is preferentially expressed in mature anther was isolated from a lily cDNA library. Northern blot analysis and plaque hybridization experiments showed that the LMP131A mRNA is present at ca. 0.3% of the mRNA in mature pollen and is not detectable in carpel, petal, floral bud, leaf, or root. The clone contains an open reading frame of 139 amino acid residues which shows greater than 40% sequence identity in a 91 amino acid overlap to animal actin-depolymerizing factors (ADF), cofilin and destrin. The sequences at and near the actin-binding site are most conserved. Using the lily clone as a probe, a cDNA clone, BMP1, was isolated from a mature anther library of Brassica napus. The expression pattern of the BMP1 clone was the same as that of the lily clone. The Brassica anther-preferential clone contains an open reading frame which is 79% identical to the lily LMP131A protein. Southern blot analysis showed that there are one or a few copies of the putative ADF genes in B. napus and Arabidopsis thaliana.

Actin Depolymerizing Factors↗
PubMed1993

Identification of methyl jasmonate and salicylic acid response elements from the nopaline synthase (nos) promoter.

Transgenic tobacco plants carrying a fusion between the nopaline synthase (nos) promoter and chloramphenicol acetyltransferase (CAT) reporter gene (cat) were studied for their inducibility by salicylic acid (SA) or methyl jasmonate (MJ) treatments. Either chemical significantly increased CAT activity to a level much higher than that achieved by wounding. Northern blot analysis showed a corresponding increase in mRNA levels. After 20 h of induction of flowering plants, the response to MJ treatment was weaker in old leaves compared with young leaves, whereas the SA response was stronger in old leaves. Kinetic experiments showed that the SA response was much faster than the MJ response, suggesting that the induction mechanism of the nos promoter by these chemicals may differ. Deletion analysis showed that both SA and MJ responses require the DNA sequence between -119 and -112 from the transcription initiation site. This region contains the hexamer sequence (TGACGT) that has been found to be an important regulatory element for several promoters. The MJ response was also reduced by deletions of the CAAT box region or the sequence between -112 and -101, whereas the SA response was not significantly affected by these deletions. This suggests that the nos upstream region containing the hexamer motif is essential for the SA or MJ response and that the CAAT box region and the sequence immediately downstream from the hexamer motif are required for maximum induction by MJ.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1993

Nucleotide sequence and characterization of the traABCD region of IncI1 plasmid R64.

A 3.6-kb BglII-SmaI segment of the transfer region of IncI1 plasmid R64drd-11 was sequenced and characterized. Analysis of the DNA sequence indicated the presence of four genes, traA, traB, traC, and traD, in this region. The expression of the traB, traC, and traD genes was examined by maxicell experiments and that of the traA gene was examined by constructing the traA-lacZ fusion gene. The introduction of frameshift mutations into the four genes indicated that the traB and traC genes are essential for conjugal transfer in liquid medium and on a solid surface. Both were also required for the formation of the thin pilus, which is the receptor for phages I alpha and PR64FS. Upstream of the traA gene, a promoter sequence for sigma 70 of E. coli RNA polymerase was identified by S1 nuclease mapping and primer extension experiments.

Amino Acid Sequence↗
PubMed1992

Molecular cloning and characterization of catechol 2,3-dioxygenases from biphenyl/polychlorinated biphenyls-degrading bacteria.

Catechol 2,3-dioxygenases were cloned from Alcaligenes sp. KF711, Pseudomonas putida KF715, and Achromobacter xylosoxidans KF701 which are biphenyl/polychlorinated biphenyls-degrading bacteria. All of the cloned enzymes were purified by preparative polyacrylamide gel electrophoresis (PAGE). The purified catechol 2,3-dioxygenases were significantly different from one another in ring-fission activities to catechol and its derivatives. The catechol 2,3-dioxygenase from Alcaligenes sp. KF711 exhibited higher ring-fission activity to 4-chlorocatechol than those from P. putida KF715 and A. xylosoxidans KF701. In electrophoretic mobilities, the three enzymes were different from one another on nondenaturing PAGE but the same on SDS-PAGE.

Alcaligenes↗
PubMed1992

Inhibition of Sucrose Enhancer Effect of the Potato Proteinase Inhibitor II Promoter by Salicylic Acid.

Effect of salicylic acid (SA) on the expression of the potato proteinase inhibitor (PI) II promoter was studied with transgenic tobacco plants (Nicotiana tabacum) carrying a gene fusion between the PI-II promoter and the chloramphenicol acetyltransferase (cat) reporter. As previously observed, the PI-II promoter was inducible by wounding and the promoter activity was further enhanced by sucrose. Addition of SA did not influence the wound induction of the PI-II promoter but significantly inhibited the sucrose response. The 5'-deletion mutant -573 was unable to respond to wounding but did respond to sucrose and SA. The 3'-deletion analysis indicated the presence of a sucrose-responsive element between -574 and -520. A study of the insertion mutants revealed the function of another sucrose-responsive element between -522 and -500. Enhancer effects of these sucrose-responsive elements were inhibited by SA. These studies suggest that SA inhibits PI-II promoter activity by decreasing the sucrose response. Analysis of SA-related chemicals revealed that only acetyl-SA showed a similar inhibitory effect, and other hydroxybenzoic acids had little or no effect on the sucrose enhancer activity. Therefore, it seems that the interaction between SA and the receptor molecule is specific.

Journal Article↗