A stable halosilylene at room temperature in THF solution.
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Journal Article↗
Biomedical subjects
H M Cho
Publications and source records attributed to H M Cho.
Background monitoring and long-range transport of atmospheric CFC-11 and CFC-12 at Kosan, Korea.
The background concentrations of atmospheric CFC-11 and CFC-12 were monitored to assess their impact on stratospheric ozone depletion and global warming from September 1995 to March 1999 at Kosan, Korea, located at eastern margin of the Asian Continent. The concentrations of atmospheric CFC-11 at Kosan have decreased slightly, at a rate of -2.5 pptv yr(-1), over the period in response to the Montreal Protocol. The CFC-12 mixing ratio at Kosan continues to increase in the atmosphere at a rate of 5.7 pptv yr(-1) despite international regulations, because of its extreme atmosphere persistence. Recent trends of these two chlorofluorocarbons at Kosan, Korea were concordant with those of the northern hemispheric background monitored unit at Mauna Loa, Hawaii. The maximum seasonal mean mixing ratios of CFC-11 and CFC-12 at Kosan, Korea, were 270 +/- 4 pptv in the spring and 538 +/- 9 pptv in the winter, and the corresponding seasonal minima were 267 +/- 7 and 529 +/- 12 pptv. This occurred in the summer and was due to southeasterly winds from the northwestern Pacific Ocean. By performing a three-day isentropic backward trajectory analysis, it was shown that air masses at Kosan, and with the exception of summer, mainly originated from central and northern China. In particular, the mixing ratios of these two contaminant species are closely related with their air mass trajectories.
Air Movements↗
Expression of the apolipoprotein C-II gene during myelomonocytic differentiation of human leukemic cells.
Apolipoprotein C-II (apoC-II), which is known to activate lipoprotein lipase (LPL), was identified by ordered differential display (ODD)-polymerase chain reaction (PCR) as a cDNA fragment exhibiting a distinct increase in expression during 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced differentiation of promonocytic U937 cells into monocytes and macrophages. The amount of apoC-II mRNA expression detectable in U937 cells significantly increased and reached a maximum 24-48 h after treatment with 32 nM TPA. apoC-II mRNA was also detected in monocytic THP-1 cells but was not detected in promyelocytic HL-60 cells. In healthy human tissues, the most significant expression of apoC-II mRNA was in the liver. Although apoC-II mRNA expression was markedly up-regulated during the induced differentiation of HL-60 cells into monocytes and macrophages with 32 nM TPA, such expression was not induced during the differentiation of HL-60 cells into granulocytes with 1.25% dimethyl sulfoxide. These results suggest that human apoC-II expression is induced at the transcription level during myelomonocytic differentiation and may confer an important role to macrophages involved in normal lipid metabolism and atherosclerosis.
3T3 Cells↗
Nucleotide sequence and differential expression of the human 3-phosphoglycerate dehydrogenase gene.
The nucleotide sequence of Hs 3-PGDH gene, encoding human 3-phosphoglycerate dehydrogenase that catalyzes the initiating step in the phosphorylated pathway of serine biosynthesis, has been determined. The 3-PGDH gene has a predicted 533 amino acid open reading frame, encoding a 56.8kDa protein that shares 94.0% similarity with rat-liver 3-PGDH. Two different transcripts corresponding to 3-PGDH mRNA were detected in human normal tissues. A dominant 2.1kb transcript was expressed at high levels in prostate, testis, ovary, brain, liver, kidney, and pancreas, and weakly expressed in thymus, colon, and heart. A 710bp transcript also appeared as a weaker band where the 2.1kb mRNA was expressed, and it was more significant than the 2.1kb mRNA in heart and skeletal muscle. The TPA-induced monocytic differentiation of U937, which also resulted in growth arrest, abruptly downregulated the expression of 3-PGDH. Removal of TPA restored cell growth through the retrodifferentiation process and subsequent expression of 3-PGDH. The 3-PGDH mRNA was markedly expressed in human leukemias, lymphoma Sup-T1, colon adenocarcinoma COLO 320DM, epitheloid carcinoma HeLa S3, and murine lymphoma BW5147.G.1.4, but not in human leukemia K562. This report demonstrates that the human 3-PGDH gene is regulated at the transcriptional level depending on tissue specificty and cellular proliferative status, and its transcriptional regulation mechanism may be a useful target for diagnosis and therapy of cancer.
3T3 Cells↗
Effect of ursodeoxycholic acid on experimental hepatic porphyria induced by griseofulvin.
Griseofulvin(GF) has become the drug of choice as an antifungal agent for patients who suffer from many kinds of fungal infection. In order to clarify hepatic injury by griseofulvin(GF) overload and the effect of UDCA on GF-induced hepatic injury, the authors carried out biochemical, histologic, and ultrastructural studies of liver following treatment with griseofulvin and ursodeoxycholic acid(UDCA) in mice. Urine porphobilinogen excretion in the group treated with GF alone was significantly increased and reached the highest level in the 4th week and declined thereafter. Biochemical studies of the liver function showed no remarkable changes of serum bilirubin levels throughout the experimental period in all groups, except for SGPT and alkaline phosphatase activities which were significantly elevated and reached the highest level in the second week. Then they slightly decreased in GF treated groups(GF alone and GF plus UDCA) in comparison with the control group. Pathologic findings in the group treated with GF alone include focal liver cell necrosis(esp, zone 3), Mallory bodies in hepatocytes(esp, zone 1), Kupffer cell activation, and brown protoporphyrin pigments in the hepatocytes, bile canaliculi and interlobular bile ducts with a marked inflammatory cell infiltration in the portal tracts. Under the polarizing light microscope, bile ductular and canalicular thrombi showed a "Maltese cross" birefringence in mice treated with GF alone. There is no definite finding of fatty change in hepatocyte. Under the microscope, the liver appeared normal with an intact lobular architecture in the GF plus UDCA treated group. Electron microscopically, GF-induced changes include swelling of mitochondria, globular protoporphyrin crystals in the hepatocyte cytoplasm, markedly dilated bile cannaliculi and bile ducts and the formation of a Mallory hyaline bodies in the hepatocytes. There were no noticeable structural changes in the GF plus UDCA-treated group. Therefore the results suggest that GF causes hepatic injury, namely porphyria and cholestasis, and the treatment of UDCA may have cytoprotective and choleretic effects on GF-induced hepatic injuries.
Alanine Transaminase↗
A case of subcutaneous seeding of hepatocellular carcinoma after fine needle aspiration biopsy.
Cancer spread along the needle track following fine needle aspiration biopsy is said to be a rare complication. The authors report a case of subcutaneous implantation of hepatocellular carcinoma following ultrasono-guided fine needle aspiration biopsy. The patient, a 67-year-old Korean male was found to have a large hepatocellular carcinoma diagnosed by fine needle aspiration biopsy. Four months later, the patient felt two subcutaneous growing lumps at the previous aspiration site. The authors confirmed them histologically 11 months after aspiration.
Aged↗
Light saturation curves and quantum yields in reaction centers from photosynthetic bacteria.
Reaction centers isolated from the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26 mutant were irradiated with laser pulses of variable energy and the amount of photooxidation of the primary electron donor bacteriochlorophyll was measured. The resultant light saturation curve fits an exponential function and not a hyperbolic or hyperbolic tangent function. Analysis using either a Poisson statistical model or a simple kinetic model predicts an exponential light saturation curve in the limit where the light pulse is long relative to any transient intermediate states. The absolute quantum yield of photochemistry was found to be 0.98, utilizing the entire light saturation curve. Distortions from the simple exponential light saturation behavior are predicted when very short laser pulses are used.
Kinetics↗