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Biomedical subjects

J Song

Publications and source records attributed to J Song.

At least 271 records · Page 15Linked to original sources
PubMed1997

Identification of apo(a) phenotypes in a Korean population using a standardized nomenclature system based on the number of kringle IV repeats.

We determined serum lipoprotein(a) [Lp(a)] concentrations and apolipoprotein(a) [apo(a)] phenotypes in 193 healthy Koreans. We analysed the apo(a) phenotypes by a simplified sodium dodecyl sulphate-polyacrylamide gel electrophoresis method and classified apo(a) isoforms objectively using an apo(a) phenotype standard with a known number of kringle IV repeats. The frequency distribution of Lp(a) levels showed marked positive skew with a mean of 0.143 g/L and a median of 0.052 g/L. Of the 193 subjects tested, no bands were detected in three, and single- and double-band phenotypes were observed in 103 and 87, respectively. Among the Koreans, the most frequent phenotype was S5(39.4%), followed by S4S5(17.1%), S5S5(14.0%), S4(11.4%), S3S5(5.2%), and the remaining phenotypes (13.0%). The calculated apo(a) allele frequencies were LpF, 0.003; LpS1, 0.013; LpS2, 0.010; LpS3, 0.048; LpS4, 0.198; LpS5, 0.563 and Lp0, 0.165. We found that the serum Lp(a) concentration in Koreans was similar to that of Caucasians, but the apo(a) allele size distribution was shifted toward higher molecular weights.

Adult↗
PubMed1997

Troglitazone reduces contraction by inhibition of vascular smooth muscle cell Ca2+ currents and not endothelial nitric oxide production.

The insulin-sensitizing compound troglitazone has evolved into a promising therapeutic agent for type II diabetes. It improves insulin sensitivity and lipoprotein metabolic profiles and lowers blood pressure in humans and rodents. Because troglitazone has insulin-like effects on a number of tissues, we hypothesized that it may reduce vascular tone through stimulation of endothelial-derived nitric oxide (NO) production or by diminution of vascular smooth muscle cell (VSMC) intracellular calcium ([Ca2+]i). Our results show that troglitazone decreases norepinephrine-induced contractile responses in the rat tail artery, an effect not reversed by the NO inhibitor L-nitroarginine methyl ester (L-NAME). In contrast, troglitazone significantly inhibited L-type Ca2+ currents in freshly dissociated rat tail artery and aortic VSMCs and in cultured VSMCs. The data suggest that troglitazone attenuates vascular contractility via a mechanism involving VSMC [Ca2+]i but independent from endothelial generation of NO. Because insulin has been shown to affect vascular tone by both of these mechanisms, troglitazone only partially mimics insulin action in this tissue.

Analysis of Variance↗
PubMed1997

National cholesterol treatment guidelines in Korean population--setting-up the cutpoints for high blood cholesterol.

National Cholesterol Treatment Guidelines are different according to race and country, and change year by year, because the distribution of lipid and lipoprotein levels are different by genetic background, dietary habit and life style. So it is mandatory to set-up the national cholesterol treatment guidelines based on the epidemiologic results. To establish the cutpoints for hypercholesterolemia specific to the Korean population, we selected the laboratories, whose inaccuracies of cholesterol measurement were less than 5%, in the external laboratory quality assessment survey, and performed epidemiological survey on the distribution of cholesterol levels, and other risk factors of coronary heart disease (CHD). As a result, prevalence of CHD risk factors was very high in hypertension (28.0%) and relatively low in diabetes (2.8%). Smokers were 42.6% of total subjects. Thirteen percent of subjects had a family member(s) who was suffering from or had of hypertension, stroke, and heart diseases. The average cholesterol level of a Korean was 187 mg/dL, which was about 25 mg/dL lower than that of United States. The 75th percentile to total cholesterol was 210 mg/dL and 90th percentile 235 mg/dL. The cutpoint for borderline-high cholesterol levels provide a major guideline for initiation of dietary and exercise therapy. We propose the cutpoint for borderline-high cholesterol levels as 200 instead of 210 mg/dL to initiate more active dietary and exercise therapy, and we also propose the temporary cutpoint for high blood cholesterol levels as 240 mg/dL instead of 235 mg/dL, which is a reasonable cutpoint considering medical insurance policy of the country. In conclusion, we suggest the cutpoints for borderline-high and high serum cholesterol levels as 200 and 240 mg/dL, respectively.

Adult↗
PubMed1997

[Changes of [Ca2+]i in colorectal cancer cells induced by some chemicals].

Changes of [Ca2+]i in CCL229 cells induced by retionoic acid (RA), 1,25(OH)2VD3 and PMA were measured by spectrofluorometry. The effects of endoplasmic reticulum (ER)-specific Ca(2+)-ATPase inhibitor thapsigargin (TG) and IP3 receptor inhibitor heparin on RA-induced changes of [Ca2+]i were observed and the relationship between RA-induced changes of [Ca2+]i and ER was also investigated. The results showed that [Ca2+]i increased markedly in several seconds after treated by RA and 1,25(OH)2VD3. When cells were pretreated with EGTA and verapamil (Ca2+ entry blocker drug), TG could not inhibit RA-stimulated Ca2+ release from intracellular calcium pools and TG could increase [Ca2+]i after pretreated by RA. In addition, heparin could not completely inhibit RA-induced [Ca2+]i increase. The results suggest that RA might stimulate IP3-sensitive pool or IP3-insensitive pool on ER to increase [Ca2+]i, or there might be RA-sensitive calcium pools except ER in cells.

Antineoplastic Agents↗
PubMed1997

[Effects of diesel exhaust particle on gap junction intercellular communication].

Scrape-loading and dye transfer technique (SLDT) was used to study the effects of diesel exhaust particle (DEP) on gap junction intercellular communication (GJIC). The results demonstrated that the extract of DEP caused inhibition of gap junction intercellular communication in Balb/c 3T3 cells. It was suggested that inhibition of gap junction intercellular communication in cells may be one of the cause to induce cell transformation.

3T3 Cells↗
PubMed1997

[Closely relationship between expression of endoplasmic reticulum molecular chaperone Grp94 and c-myc oncogene in human colorectal carcinoma cell lines].

OBJECTIVE: To study the biological significance of Grp94 deleted product (Grp94 beta) expressed in human colorectal carcinoma cells. METHODS: The relationship between molecular chaperone Grp94 and c-myc oncogene expression in the human colorectal carcinoma cell line CCL229, CX-1 and retinoic acid (RA) induced CCL229 by both of digoxin labelled c-myc cDNA probe spot by-bridization and RT-PCR with endoplasmic reticulum molecular chaperone Grp94 proximal 3' end oligonucletide primers was investigated. RESULTS: In CCL229 cells, the expression of Grp94 beta and c-myc oncogene are significantly higher than those in CX-1 cells. Along with the RA inducing, both decreased with one accord, and to the lowest level after six days induction. CONCLUSION: The Grp94 normal expression (Grp94 alpha), which was undetectable in CCL229 cells increased after RA induction. The results showed that the expression of Grp94 beta may be closely related to that of c-myc oncogene. It is suggested that the Grp94 be related to some biological characteristics of cancer, for example, the invasiveness.

Antineoplastic Agents↗
PubMed1997

[The plant regeneration of Salvia miltiorrhiza Bge. transformed by Agrobacterium].

The hairy roots and crown galls of Salvia miltiorrhiza were obtained by infecting plant with A. rhizogenes (strain 15834, LBA 9402) and A. tumefaciens (strain C58). The transformed plants were regenerated light and transplanted form cultural medium into soil successfully. The plants transformed by A. rhizogenes have characteristics of short stems and develop hairy roots, those and trans formed by A. tumefaciens grow vigorously featuring, longer stems and well developed roots. Both biomass production and tanshenone content are higher than the original plant.

Agrobacterium tumefaciens↗
PubMed1997

[Measurement and evaluation of radiation dose distribution of gamma-ray altimeter in static test for recovery capsule during simulated landing].

The gamma-ray altimeter, containing a gamma-radioactive source 137Cs with activity of 2.96 x 10(10) Bq, was used to detect the height of the spacecraft recovery capsule during landing. To measure the gamma-dose distribution near to the guidance section, especially at position where the useful load is located in recovery capsule, gamma-dose field at the test-site for one machine test was measured by means of a gamma-dose rate meter FJ-317C and a gamma-dose meter ANRI-01-02. The result showed that the absorbed dose rate at 5 meters from gamma-source on the ground is as low as the radiation protection limit when the altimeter is down to 0.16 m from the ground. The ground reflection effect for gamma-ray decreases as height of the recovery capsule increases. Therefore, the gamma-dose level at useful load in the recovery capsule will meet the requirements of flight safety.

Altitude↗
PubMed1997

[The antibechic, expectorant and antiasthmatic actions of Cynanchum komarovii].

The water and ethanol extracts of Lao Gua Tou (Cynanchum komarovii) is effective on relieving cough caused by the irritation of ammonnia water in mice. The extract can increase the secretion of repiratory tract and promote expectoration, also alleviate asthma induced by histamine and acetylcholing chloride in guinea pigs.

Animals↗
PubMed1997

Selection of a high tanshinone-producing crown gall strain and production of tanshinone in the strain.

Crown galls were induced by direct infection of sterile seedlings of Salvia miltiorrhiza with Agrobacterium tumefaciens C58 and subcultured on a 67-V hormone-free medium by successively selecting red cell aggregates. A high tanshinone-producing crown gall strain C1 was obtained after 12 months in a subculture. It grows well and retains its high tanshinone-producing characteristic in liquid stationary cultures. It is obvious that the yeast extract and fermentation extract of Armillaria mellea as elicitors promote strain C1 to produce tanshinone. Tanshinone content of strain C1 cultures was over three times higher than that of the crude drugs. The results indicated that the crown gall tissue and elicitor technique could provide some new clues for the production of tanshinone under the condition of a liquid stationary culture.

Abietanes↗
PubMed1997

Concept formation and problem-solving following closed head injury in children.

To further investigate the usefulness of 3 purported measures of executive function (EF) in head injured children, we administered the Twenty Questions Test (TQT), Tower of London (TOL), and the Wisconsin Card Sorting Test (WCST) to 151 children who had sustained a closed head injury (CHI) of varying severity about 3 years earlier. In addition, we tested 89 normal controls. Fifty-seven of the patients were included in a longitudinal study that compared performance at 3 months and 36 months. All of the head injured children underwent magnetic resonance imaging for investigational purposes. Severity of CHI, as defined by the lowest Glasgow Coma Scale (GCS) score, affected performance on all 3 EF measures. Focal lesion volume incremented prediction of performance on TOL and WCST, but not TQT. Moderate intercorrelations of the test variables were obtained. Although all three EF measures depicted changes in performance over 3 years, a ceiling effect detracted from the sensitivity of the TOL to the impact of CHI on development. Implications of the findings for clinical applications are discussed.

Adolescent↗
PubMed1996

Partial constitutive activation of pheromone responses by a palmitoylation-site mutant of a G protein alpha subunit in yeast.

G protein alpha subunits are often myristoylated and/or palmitoylated near their amino terminus. The G protein alpha subunit in the yeast Saccharomyces cerevisiae (GPA1 gene product, Gpa1p) is known to be myristoylated, and this modification is essential for G protein activity in vivo. Here we examined whether Gpa1p is palmitoylated and determined the functional consequences of this modification. [3H]-Palmitic acid was incorporated into Gpa1p in cells expressing myc-tagged Gpa1p or Gpa1p-Gst. The label was released upon hydroxylamine treatment. Substitution of the conserved Cys 3 for Ser blocked incorporation of the label (Gpa1pC3S). Palmitoylation was also blocked by a mutation that prevents myristoylation (Gly2Ala), whereas the palmitoylation-site mutation had no effect on myristoylation of Gpa1p. Gpa1pC3S complemented the gpa1 delta mutation in vivo and formed a complex with G beta gamma that was able to undergo nucleotide exchange in vitro. However, basal and pheromone-induced FUSl-lacZ transcription were 2-5-fold higher in the C3S mutant. Pheromone-induced growth arrest was also enhanced by the mutation, but recovery from arrest was not affected. Like wild-type Gpa1p, the C3S mutant was predominantly membrane-associated. Upon Triton X-114 partitioning or high pH treatment, no difference in the membrane-binding properties of the wild-type Gpa1p and the C3S mutant was detected. By sucrose density gradient centrifugation of membranes, however, most of the mutant protein was mislocalized to a non-plasma membrane compartment, whereas G beta gamma localization was unaltered. Taken together, our data suggest that Gpa1p is palmitoylated via a thioester bond at Cys 3 and that palmitoylation plays a role in modulating Gpa1p signaling and membrane localization.

Cell Membrane↗
PubMed1996

Characterization and mapping of cDNA encoding aspartate aminotransferase in rice, Oryza sativa L.

Fifteen cDNA clones, putatively identified as encoding aspartate aminotransferase (AST, EC 2.6.1.1.), were isolated and partially sequenced. Together with six previously isolated clones putatively identified to encode ASTs (Sasaki, et al. 1994, Plant Journal 6, 615-624), their sequences were characterized and classified into 4 cDNA species. Two of the isolated clones, C60213 and C2079, were full-length cDNAs, and their complete nucleotide sequences were determined. C60213 was 1612 bp long and its deduced amino acid sequence showed 88% homology with that of Panicum miliaceum L. mitochondrial AST. The C60213-encoded protein had an N-terminal amino acid sequence that was characteristic of a mitochondrial transit peptide. On the other hand, C2079 was 1546 bp long and had 91% amino acid sequence homology with P. miliaceum L. cytosolic AST but lacked in the transit peptide sequence. The homologies of nucleotide sequences and deduced amino acid sequences of C2079 and C60213 were 54% and 52%, respectively. C2079 and C60213 were mapped on chromosomes 1 and 6, respectively, by restriction fragment length polymorphism linkage analysis. Northern blot analysis using C2079 as a probe revealed much higher transcript levels in callus and root than in green and etiolated shoots, suggesting tissue-specific variations of AST gene expression.

Amino Acid Sequence↗
PubMed1996

Regulation of membrane and subunit interactions by N-myristoylation of a G protein alpha subunit in yeast.

Initiation of the mating process in yeast Saccharomyces cerevisiae requires the action of secreted pheromones and G protein-coupled receptors. As in other eukaryotes, the yeast G protein alpha subunit undergoes N-myristoylation (GPA1 gene product, Gpa1p). This modification appears to be essential for function, since a myristoylation site mutation exhibits the null phenotype in vivo (gpa1(G2A)). Here we examine how myristoylation affects Gpa1p activity in vitro. We show that the G2A mutant of Gpa1p, when fused with glutathione S-transferase, can still form a complex with the G protein betagamma subunits. The complex is stabilized by GDP and is dissociated upon treatment with guanosine 5'-O-(thiotriphosphate). In addition, there is no apparent difference in the relative binding affinity of Gbetagamma for mutant and wild-type Gpa1p. Using sucrose density gradient fractionation of cell membranes, Gpa1p associates normally with the plasma membrane whereas Gpa1pG2A is mislocalized to a microsomal membrane fraction. A portion of Gbetagamma is also mislocalized in these cells, as it is in a gpa1Delta strain. In contrast, wild-type Gpa1p reaches the plasma membrane in cells that do not express Gbetagamma or cell surface receptors. These findings indicate that mislocalization of Gpa1pG2A is not caused by a redistribution of Gbetagamma, nor is it the result of any difference in Gbetagamma binding affinity. These data suggest that myristoylation is required for specific targeting of Gpa1p to the plasma membrane, where it is needed to interact with the receptor and to regulate the release of Gbetagamma.

Base Sequence↗
PubMed1996

A rapid polarographic immunoassay based on the anodic current of metal labeling.

A heterogeneous voltammetric immunoassay of human serum albumin (HSA) based on the anodic current of metal labeling was studied. HSA was covalently coupled to diethylenetriaminepentaacetic anhydride and labeled with In3+. A heterogeneous competitive immunochemical reaction was carried out in the wells of a microtiter plate. The In3+ label was released in 1 M HCl solution and determined by simplified anodic stripping neopolarography. HSA could be detected in the concentration range of 4.0-50 microg ml-1. The method was used to determine HSA in serum specimens, and the results were in good agreement with those obtained with dye binding spectrophotometry.

Chelating Agents↗
PubMed1996

XFGF-9: a new fibroblast growth factor from Xenopus embryos.

We have identified the Xenopus homologue of mammalian FGF-9 (XFGF-9). Sequence comparison between Xenopus and mammals shows that they share 93% identity at the amino acid level, making FGF-9 the most highly conserved member within the family. The sequence shows that there is no N-terminal signal sequence but that there is an internal hydrophobic sequence resembling a transmembrane domain. By using an in vitro translation system, we demonstrate that XFGF-9 can be glycosylated by microsomes but shows no signal peptide cleavage. This suggests that it can be secreted using the internal hydrophobic domain to cross the endoplasmic reticulum membrane. Expression studies using RNAse protections and in situ hybridization show that XFGF-9 is expressed both maternally and zygotically. The maternal mRNA is detected at a higher level than other forms (XFGF-2 and eFGF), mainly in the animal hemisphere. A proportion of the maternal transcript persists until the early gastrula stage when it is joined by zygotic expression around the blastopore region, and thereafter the mRNA content shows some increase during further development. Zygotic XFGF-9 is expressed uniformly along the dorsal axis, as well as in the head region. We have expressed recombinant XFGF-9 protein in bacteria, and show that it has a mesoderm-inducing activity in the animal cap assay, with a similar specific activity to other fibroblast growth factor (FGFs). We have injected a synthetic mRNA into eggs, and show that it has both mesoderm-inducing activity in animal caps and also a posteriorizing activity in whole embryos. The levels of biological activity shown by the XFGF-9 mRNA injections compared to XFGF-2 and eFGF show that there is at least some extracellular function. This supports the biochemical results, suggesting that the protein has at least some capacity to be secreted.

Amino Acid Sequence↗