• The Korean Journal of Nuclear Medicine
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• v.34 no.4
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• pp.294-302
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• 2000

Purpose: To investigate the mechanisms related to F-18-FDG uptake by tumors, F-18-FDG accumulation was compared with glucose transporter-1 (Glut-1) expression and hexokinase activity in various human cancer cell lines. Materials and Methods: Human colon cancer (SNU-C2A, SNU-C4, SNU-C5), hepatocellular carcinoma (SNU-387, SNU-423, SNU-449), lung cancer (NCI-H522, NCI-H358, NCI-H1299), uterine cervical cancer (HeLa, HeLa 229, HeLa S3) and brain tumor (A172, Hs 683) cell lines were used. After 24 hr incubation of $5{\times}10^5$ cells, 37 kBq F-18-FDG was added and the uptake by cells at 10 min was measured using a gamma counter. Hexokinase activity was measured by continuous spectrophotometric rate determination. To measure mitochondrial hexokinase activity, mitochondrial fraction was separated by a high speed centrifuge. Immunohistochemical staining of Glut-1 was performed, and graded as 0, 1, 2, or 3 according to expression. Results: There was difference among F-18-FDG uptake, total and mitochondrial hexokinase activity, and Glut-1 expression with different cancer cell lines. The correlations of F-18-FDG with total hexokinase and mitochondrial hexokinase activity were low (r=0.27 and 0.26, respectively). Glut-1 expression showed a good correlation with F-18-FDG uptake (p=0.81, p=0.0015). Previously, we reported no correlation of F-18-FDG uptake with hexokinase activity in colon cancer cell lines. Thus, when colon cancer cells were excluded, F-18-FDG uptake showed higher correlation with total hexokinase and mitochondrial hexokinase activity (r=0.81, p=0.0027 and r=0.81, p=0.0049, respectively). Conclusion: Both Glut-1 expression and hexokinase activity were contributing factors related to F-18-FDG accumulation in human cancer cell lines. The relative contribution of Glut-1 expression and hexokinase activity, however, was different among different cancer cell types.

• Journal of Life Science
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• v.11 no.5
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• pp.476-482
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• 2001

The study was undertaken to determine the effect of the aqeuous extract of sea tangle, Laminaria japonicus, on the activites of glucokinase and hexokinase in the pancreas of diabetic mellitus mice which were induced by alloxan. After one week of alloxan injection, the levels of serum glucose and insulin secretion were dramatically increased, however, the insulin secretion was decreased with administration of sea tangle extract. Alloxan injection allowed the serum glucose level to increase and level was decreased by sea tangle extract administration. Furthermore, it was observed the sea tangle extract was effective in recovering the levels of insulin secretion. Enzyme activities of the glucokinase and hexokinase were decreased by alloxan treatment. In contrast, sea tangle extract administration to the mice allowed to increase proportionally. These results suggested that sea tangle extract is highly effective in treatment of diabetic mellitus induced by alloxan.

• The Journal of Dong Guk Oriental Medicine
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• v.7 no.1
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• pp.65-74
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• 1998

We investigated the in vivo effect of an aquous extract from Rhois Galla (R-G) on glucokinase and hexokinase activities of diabetes mellitus induced by interleukin-$1{\beta}$ ($IL-1{\beta}$). After 1 week of alloxan injection, the levels of serum glucose and insulin secretion were dramatically increased, however, the insulin secretion was decreased with administration of R-G. $IL-1{\beta}$ injection allowed the serum glucose level increased and the level was decreased by R-G administration. Furthermore, we could observe that R-G was effective in recovering the levels of insulin secretion. Enzyme activities of the glucokinase and hexokinase were decreased by $IL-1{\beta}$ treatment In contrast, R-G administration to the mice allowed proportion increasing. Seemingly, when $IL-1{\beta}$ was injected to the mice, enzyme activities of the glucokinase and hexokinase were decreased. But, R-G stimulated induction of enzyme activities of the glucokinase and hexokinase as high as normal group. These results suggested that R-G is highly effective in treatment of diabetes mellitus.

• The Journal of Internal Korean Medicine
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• v.19 no.1
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• pp.466-476
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• 1998

We investigated the in vivo effect of an aqueous extract (referred to as EF) from Eriobotryae folium on glucokinase and hexokinase activities of diabetes mellitus induced by $interleukin-1{\beta}\;(IL-1{\beta})$. After 1 week of $IL-1{\beta}$ injection, the levels of serum glucose concentration and insulin secretion were dramatically increased. However, the insulin secretion was decreased with administration of EF. The level of glucose concentration was decreased by EF administration. Furthermore, it was observed that EF was effective in recovering the levels of insulin secretion. Enzyme activities of the glucokinase and hexokinase, which are key enzymes of glucose phosphorylastion, were decreased by $IL-1{\beta}$. EF administration to the mice allowed proportional increasing by stimulation of induction of enzyme activities as high as normal group. These results suggested that EF is highly effective in treatment of diabetes mellitus induce by $IL-1{\beta}$.

• The Korean Journal of Nuclear Medicine
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• v.33 no.1
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• pp.1-10
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• 1999

Cancer cells are known to show increased rates of glycolysis metabolism. Based on this, PET studies using F-18-fluorodeoxyglucose have been used for the detection of primary and metastatic tumors. To account for this increased glucose uptake, a variety of mechanisms has been proposed. Glucose influx across the cell membrane is mediated by a family of structurally related proteins known as glucose transporters (Gluts). Among 6 isoforms of Gluts, Glut-1 and/or Glut-3 have been reported to show increased expression in various tumors. Increased level of Glut mRNA transcription is supposed to be the basic mechanism of Glut overexpression at the protein level. Some oncogens such as src or ras intensely stimulate Glut-1 by means of increased Glut-1 mRNA levels. Hexokinase activity is another important factor in glucose uptake in cancer cells. Especially hexokinase type II is considered to be involved in glycolysis of cancer cells. Much of the hexokinase of tumor cells is bound to outer membrane of mitochondria by the porin, a hexokinase receptor. Through this interaction, hexokinase may gain preferred access to ATP synthesized via oxidative phosphorylation in the inner mitochondria compartment. Other biologic factors such as tumor blood flow, blood volume, hypoxia, and infiltrating cells in tumor tissue are involved. Relative hypoxia may activate the anaerobic glycotytic pathway. Surrounding macrophages and newly formed granulation tissue in tumor showed greater glucose uptake than did viable cancer cells. To expand the application of FDG PET in oncology, it is important for nuclear medicine physicians to understand the related mechanisms of glucose uptake in cancer tissue.

• Korean Journal of Clinical Laboratory Science
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• v.39 no.1
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• pp.25-30
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• 2007

In this study, the two sampling methods for blood glucose measurement were evaluated in order to reduce pre-analytical error. For this purpose, glucose levels of Li-heparinized plasma (LHP) and Na-fluorinated plasma (NFP) in blood collected from healthy volunteers were determined by using routine hexokinase procedures. The percentage range of pre-analytical error was quantitated by comparing LHP glucose values with NFP glucose values according to delaying analytical time (0, 60, and 120 min). LHP glucose values were decreased by 6.6% in 60 min., 17.7% in 120 min, whereas NFP glucose values decreased by 1.1% in 60 min, 2.0% in 120 min. Therefore it may be recommended that the NFP sampling method should be used for routine blood glucose determination in diabetes mellitus diagnosis.

• The Journal of Dong Guk Oriental Medicine
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• v.6 no.1
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• pp.151-161
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• 1997

We have investigated the in vivo. effect of an aqeuous extract from Eriobotryae folium on glucokinase and hexokinase activities of diabetes mellitus induced by alloxan. After 1 week of alloxan injection, the levels of serum glucose and insulin secretion were dramatically increased, however, the insulin secretion was decreased with administration of Eriobotryae folium. Alloxan injection allowed the serum glucose level increased and the level was decreased by Eriobotryae folium administration. Furthermore, it was observed that Eriobotryae folium was effective in recovering the levels of insulin secretion. Enzyme activities of the glucokinase and hexokinase were decreased by alloxan treatment. In contrast, Eriobotryae folium administration to the mice allowed proportional increasing. These results suggested that Eriobotryae folium is highly effective in treatment of diabetes mellitus induced by alloxan.

• Korean Journal of Clinical Laboratory Science
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• v.39 no.3
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• pp.249-255
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• 2007

While respiratory burst enhances neutrophil glucose utilization, many neutrophil functions are critically influenced by extracellular matrix interaction and phosphoinositide-3-OH kinase (PI3K) signaling. We thus evaluated the role of RGD integrin occupancy and PI3K inhibition on respiratory burst and [18F]FDG uptake of stimulated neutrophils. Human neutrophils were stimulated by 100 ng/mL phorbol-myristate-acetate (PMA), and respiratory burst was measured by cumulative luminescence with lucigenin. [18F]FDG uptake and total hexokinase activity was measured 20 min after PMA stimulation in the presence or absence of soluble RGD peptides (200 g/mL) and/or the PI3K inhibitor wortmannin (200 nM). PMA induced a 71.70.9 fold increase in neutrophil oxygen intermediate generation. [18F]FDG uptake was increased to $194.6{\pm} 3.7%$ and hexokinase activity to $145.0{\pm}2.0%$ of basal levels (both p<0.0005). RGD peptides attenuated respiratory burst activation to $35.6{\pm}0.2%$ (p<0.005), but did not inhibit stimulated [18F]FDG uptake or hexokinase activity. In contrast, without affecting respiratory burst activation, wortmannin inhibited PMA stimulated [18F]FDG uptake to $66.9{\pm}1.6%$ and hexokinase activity to $81.0{\pm}4.2%$ (both P<0.0005), demonstrating its dependence on PI3K activity. Neither RGD nor wortmannin reversed the other's inhibitory effect on stimulated [18F]FDG uptake and hexokinase activity or respiratory burst, which suggests the involvement of distinct signaling pathways. Neutrophil [18F]FDG uptake is enhanced by PMA through a mechanism that requires PI3K activity but is independent of integrin receptor occupancy or respiratory burst activation.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.114-115
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• 2001

Alloxan은 glucokinase효소가 기질인 glucose결합부위인 -SH기를 경쟁적으로 저해함으로서 glucose의 초기 인산화를 억제하여 당뇨병을 유도시키는 화학물질이다. 본 연구에서는 이제까지의 조직학적이고 혈청학적인 연구에서 한 단계 나아가 효소학적인 측면에서 당대사와 인슐린 분비 조절인자로 알려진 glucokinase와 혈중 당을 조직내로 흡수하여 인산화시키는 효소인 hexokinase에 대한 다시마 열수추출물의 효과를 분석 검토하였다. (중략)

• Horticultural Science & Technology
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• v.30 no.3
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• pp.243-249
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• 2012

Hexokinase is the first enzyme in the hexose assimilation pathway; it acts as a sensor for plant sugar responses, and it is also important in determining the fruit sugar levels. The full-length cDNA of a hexokinase gene was isolated from loquat through reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends, which was designated as EjHXK1. EjHXK1 is 1,839 bp long and contains an entire open reading frame encoding 497 amino acids. The predicted protein of EjHXK1 shares 72%-81% similarity with other plant hexokinases. Phylogeny analysis indicated that EjHXK1 is closely related to maize and rice hexokinases. Transient expression of the 35S: EjHXK1-GFP fusion protein was observed on the cell membrane and cytoplasm. Real-time RT-PCR indicated that EjHXK1 is expressed in loquat leaves, stems, flowers, and fruits. EjHXK1 transcripts were higher during early fruit development, but decreases before maturation, which is consistent with hexokinase enzyme activity during fruit development and conducive for hexose accumulation in mature fruits. These results imply that EjHXK1 may play important roles in the regulation of sugar flux during fruit ripening.