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Biomedical subjects

S R Kim

Publications and source records attributed to S R Kim.

102 records · Page 6Linked to original sources
PubMed1992

Identification of G-Box Sequence as an Essential Element for Methyl Jasmonate Response of Potato Proteinase Inhibitor II Promoter.

The potato proteinase inhibitor II promoter was studied to identify cis-acting regulatory sequences involved in methyl jasmonate (MJ) response using transgenic tobacco plants carrying various lengths of the promoter fused to a chloramphenicol acetyltransferase reporter gene. An internal fragment between -625 and -520 was sufficient to confer a response to MJ, wounding, or sucrose when it was placed upstream of the nos promoter -101, which contains the CAAT-TATA region. Deletion of the proteinase inhibitor II promoter sequence upstream of -611 did not affect the MJ response, but a further deletion to -573 eliminated the response. The 3'-deletion study showed that the DNA sequence downstream from -520 is dispensable. However, 3'-deletion mutant -574 did not respond to the MJ treatment. These results indicated that an element essential for the MJ response is located at the -574/-573 region where the G-box sequence (CACGTGG) is located. The G-box sequence was not required for the sucrose enhancer effect, suggesting that the MJ response mechanism is different from that of sucrose.

Journal Article↗
PubMed1992

Nucleotide sequence of the R721 shufflon.

The shufflon is a DNA region that undergoes complex rearrangement mediated by the product of a putative site-specific recombinase gene, rci. The DNA sequences of the shufflon region and the rci gene of IncI2 plasmid R721 were determined. The R721 shufflon consists of three invertible DNA segments that are homologous to the shufflon segments found in IncI1 plasmid R64. Structural analysis of open reading frames indicated that the R721 shufflon possibly functions as a biological switch for selecting one of the six pilV genes in which the N-terminal region is constant and the C-terminal region is variable. The R721 rci gene was shown to encode a basic protein of 374 amino acid residues.

Amino Acid Sequence↗
PubMed1991

Sugar response element enhances wound response of potato proteinase inhibitor II promoter in transgenic tobacco.

The promoter region of the potato proteinase inhibitor II (PI-II) gene was studied to identify cis-acting regulatory sequences involved in sugar response using transgenic tobacco plants. The 5' control region covering an 892 nucleotide sequence upstream from the cap site and a 32 nucleotide untranslated region of the PI-II promoter was able to activate a reporter chloramphenicol acetyltransferase (cat) gene by wounding or by incubating in a sugar-free medium. This wound response was further enhanced by sugar. Hexoses, disaccharides, and some trisaccharides were strong inducers whereas pentoses, deoxy sugars, sugar acids, TCA cycle intermediates, amino acids, and other carbohydrates had little effect on the promoter activity. Deletion of the sequence between -892 and -573 abolished the wound response but not the sugar response. An additional 5' deletion to -453 removed the sugar inducibility. Locations of the cis-acting regulatory elements were further elucidated by 3' deletion analysis. Deletion of the downstream region from -520 did not affect the wound or sugar response of the promoter. However, 3' deletion mutant -574 was unable to respond to sugar but did respond weakly to wounding. Further deletion to -624 abolished both responses. Therefore, it can be concluded that a wound response element is located in between -624 and -574 and that the response is further enhanced by a sugar response element located in the sequence between -573 and -520.

Agrobacterium tumefaciens↗
PubMed1990

Transfer region of IncI1 plasmid R64 and role of shufflon in R64 transfer.

To locate the transfer region of the 122-kiloase plasmid R64drd-11 belonging to incompatibility group I1, a series of deletion derivatives was constructed by in vitro recombinant DNA techniques followed by double homologous recombination in vivo. A plasmid designated pKK609 and bearing a 56.7-kilobase R64 sequence was the smallest transferable plasmid. A plasmid designated pKK610 and no longer possessing the 44-base-pair sequence of the R64 transfer system is located at one end. The other end of the R64 transfer region comprises a DNA segment of about 19 kilobases responsible for pilus formation. Shufflon, DNA with a novel rearrangement in R64, was found to be involved in pilus formation.

Chromosome Deletion↗
PubMed1989

Two-year survival: preoperative adjuvant chemotherapy in the treatment of cervical cancer stages Ib and II with bulky tumor.

The effect of preoperative adjuvant chemotherapy on the 2-year survival rate of patients with locally advanced cervical cancer (stages Ib and II with bulky tumour) was evaluated. The 54 patients first received initial chemotherapy of vinblastine, bleomycin, and cis-platinum in a combined regimen (VBP) and then radical hysterectomy. The overall histologic response rate to chemotherapy of the primary tumor confirmed in the surgical specimen was 81% including microscopic or no evidence of disease (41%, Grade III or IV). A lower than expected incidence of lymph node metastasis (20%) was found. All nodal metastasis was noted in patients with Grades I or II (P = 0.0034). Median follow-up was 36 months (range 26-60 months). Three recurrences (6%) appeared and those patients died of the disease within 24 months. Thus the 2-year tumour-free survival rate was 94%. The patients who had positive nodes more often experienced recurrence (27 vs 0%) and a lower 2-year survival rate (72 vs 100%) (P = 0.0067). All of these recurrences were found in patients with three or more positive nodes. This preliminary study suggest that preoperative adjuvant chemotherapy (VBP) is effective (1) in reducing tumour volume or the stage of the disease, (2) in curing the lymph node involvement, and (3) in improving the 2-year tumour-free survival rate. A prospective randomized study comparing radical surgery alone with preoperative adjuvant chemotherapy followed by radical surgery is in progress.

Adult↗
PubMed1989

Cloning and nucleotide sequence of the ColIb shufflon.

The R64 shufflon is a novel type of DNA rearrangement in which four DNA segments invert independently or in groups. The related plasmid ColIb carries a variant shufflon. The present sequence analysis shows that the ColIb shufflon consists of three DNA segments that are highly homologous to the A, B, and C segments of the R64 shufflon. The 329-bp D segment of R64 is not present in the ColIb shufflon. As in the case of R64, the ColIb shufflon may act as a biological switch to select one of the six open reading frames in which the N-terminal region is constant while the C-terminal region is variable.

Base Sequence↗
PubMed1989

Multiple forms of alkaline phosphatase in mouse preimplantation embryos.

Mouse embryos were extracted with 0.5% Triton X-100 and subjected to cellulose acetate electrophoresis. In fertilized eggs, two forms of alkaline phosphatase (ALP), a slow-moving form and a fast-moving form, were observed. As cleavage proceeded, the fast-moving form disappeared, and the slow-moving form, the mobility of which was similar to that of the slow-moving form of the kidney, became gradually dominant up to the blastocyst stage (named 'embryonic' form). With blastulation, another fast-moving form showing a similar mobility to the lung ALP began to appear in blastocysts and showed a transient dominance in hatched blastocysts. After implantation, both the embryonic form and the fast-moving form gradually faded, and were eventually replaced by the new form, which may be named 'fetal form' in Day 7 embryos. These results clearly demonstrated that ALP activity does exist in embryos at all stages of preimplantation development. Moreover, the changes in multiple forms of ALP correlated with embryonic development may suggest that these multiple forms may have differential roles in the process of early development.

Alkaline Phosphatase↗
PubMed1987

Distribution of shufflon among IncI plasmids.

A shufflon or clustered inversion is a novel type of DNA rearrangement originally discovered in the IncI1 plasmid R64 (T. Komano, A. Kubo, and T. Nisioka, Nucleic Acids Res. 15:1165-1172, 1987). In a 1.95-kilobase region of R64 DNA, four DNA segments inverted independently or in groups, resulting in a complex DNA rearrangement. We found similar types of shufflon in other IncI1 plasmids, including delta, pIP111, pIP565, pIP112, pIP186, R144, R163, R483, and R621a. A variant type of shufflon occurs in the IncI1 plasmid ColIb.

DNA, Bacterial↗
PubMed1985

Phosphatidyl glycerolphosphate serves as glycerolphosphate donor in polymer synthesis.

Phosphatidyl glycerolphosphate was found to serve as the glycerolphosphate donor for polymer synthesis. When CDP-diglyceride and radiolabeled glycerolphosphate were incubated with the membrane enzyme prepared from Streptococcus sanguis, active syntheses of radiolabeled lipids and polymers were observed. The synthesis of polymer was not inhibited by low concentration of unlabeled phosphatidylglycerol. When [3H, 32P]glycerolphosphate was used, the polymer synthesized contained both 3H and 32P. The lipids formed were characterized as phosphatidylglycerol and phosphatidyl glycerolphosphate. The polymers formed from the latter were characterized as lipoteichoic acid like compounds by sodium dodecylsulfate-polyacrylamide gel electrophoresis.

Chromatography, Paper↗
PubMedDate not supplied

Clinicopathological study of minimum-sized hepatocellular carcinoma: an approach to the definition of early hepatocellular carcinoma.

Clinicopathologic examination of 33 nodules from 23 cases of minimum-sized hepatocellular carcinoma (HCC), less than 15 mm in diameter, was carried out by imaging and clinical follow up. On ultrasound (US), 16 hypoechoic nodules (48%) and 15 hyperechoic nodules (45%) on angiography 7 tumour stains (21%) and on computerized tomography (CT) 3 low density nodules (9%) were detected. Of 27 nodules on lipiodol CT (LpCT), 7 lipiodol-deposited nodules (26%) were detected. Of 16 nodules on CO2US angiography (US-angiography), 7 hypervascular (44%), 5 hypovascular (31%) and 4 isovascular nodules (25%) were detected. Of 13 nodules on CT during arterial portography (CTAP), 7 perfusion defect nodules (54%) were detected. The nodules were graded according to the Edmondson & Steiner Classification. Three nodules were resected; grossly, two were not distinct and one was poorly demarcated. Histologically, they were highly differentiated with irregularly-thin trabecular-patterned HCC where portal triads were detected. Cancer cells invaded the non-cancerous liver cells by replacement, and the border between the cancerous and non-cancerous regions was unclear; the latter region manifested chronic hepatitis or liver cirrhosis without hyperplasia. Minimum-sized HCC is characteristically hypovascular in arterial and portal supply of blood, of multicentric origin and of a well-differentiated pattern. Because the three resected nodules did not damage the liver acinus structure, they were considered to be an early stage of HCC.

Adult↗
PubMedDate not supplied

Asiatic acid derivatives protect cultured cortical neurons from glutamate-induced excitotoxicity.

Asiatic acid, a triterpene of Centella asiatica (L.) Urban (Umbelliferae), has been patented as a treatment for dementia and an enhancer of cognition by the Hoechst Aktiengesellschaft (EP 0 383 171 A2). We modified the chemical structure of asiatic acid and obtained 36 derivatives of asiatic acid in an attempt to prepare neuroprotective compounds that were more efficacious than asiatic acid itself. The neuroprotective activities of these derivatives were evaluated using primary cultures of rat cortical neurons insulted with the neurotoxin, glutamate, as an in vitro screening system. Among the semi-synthesized derivatives, three derivatives significantly mitigated the neurotoxicity induced by glutamate in this screening system. The neuroprotective activities of these 3 derivatives appeared to be more powerful than that of asiatic acid itself. These 3 derivatives significantly attenuated decreases in the levels of glutathione, glutathione peroxidase and other enzymes, which participate in the cellular defense mechanisms blunting oxidative stress. Furthermore, they significantly reduced the overproduction of NO induced by glutamate. These results showed that these derivatives of asiatic acid exerted significant neuroprotective effects on cultured cortical cells by their potentiation of the cellular oxidative defense mechanism. Therefore, these agents may prove to be efficacious in protecting neurons from the oxidative damage caused by exposure to excess glutamate.

Animals↗