• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.1
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• pp.1-5
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• 2001

Field experiment was conducted during 1993-94 season to determine the pattern of nutrient uptake and productivity of maize/sweet potato intercropping system. Four levels of nitrogen (0, 50, 100 and 150kg N ${ha}_{-1}$) and four levels of potassium (0, 40, 80 and 120kg $K_2$O ${ha}_{-1}$) formed treatment variables. Plants were sampled periodically to determine dry matter and tissue concentrations of N and K in the individual plant components of intercropped maize and sweet potato. Nitrogen and potassium fertilizer did not interact significantly to nutrient uptake by any plant parts of intercropped maize and sweet potato. But application of N fertilizer independently enhanced N uptake in all the plant parts of maize and sweet potato. The uptake of N in leaf, leaf sheath, stem, husk, and cob of maize increased upto 90 days after planting (DAP) but grain continued to accumulate N till its maturity. Sweet potato exhibited a wide variation in N uptake pattern. Sweet potato leaf shared the maximum uptake of N at 50 DAP which rapidly increased at 70 DAP and then declined. Declination of N uptake by petiole and stem were observed after 120 DAP whereas N uptake by tuber increased slowly upto 90 DAP and then rapidly till harvest. Rate of applied K had very little effect on the uptake patterns in different components of intercropped maize. Pattern of K uptake by leaf, petiole and stem of sweet potato showed almost similar trend to N uptake. But uptake of K by tuber increased almost linearly with the K application. Pattern of N and K uptake by grain and tuber paralleled the grain yield of maize and sweet potato respectively. Intercropped productivity of maize and sweet potato found to be better by the application of 100kg N and 120 kg $K_2$O ${ha}_{-1}$

• BMB Reports
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• v.38 no.4
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• pp.468-473
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• 2005

The energetics of nitrate uptake by intact cells of the halotolerant cyanobacterium Aphanothece halophytica were investigated. Nitrate uptake was inhibited by various protonophores suggesting the coupling of nitrate uptake to the proton motive force. An artificially-generated pH gradient across the membrane (${\Delta}pH$) caused an increase of nitrate uptake. In contrast, the suppression of ${\Delta}pH$ resulted in a decrease of nitrate uptake. The increase of external pH also resulted in an enhancement of nitrate uptake. The generation of the electrical potential across the membrane ($\Delta\psi$) resulted in no elevation of the rate of nitrate uptake. On the other hand, the valinomycin-mediated dissipation of $\Delta\psi$ caused no depression of the rate of nitrate uptake. Thus, it is unlikely that $\Delta\psi$ participated in the energization of the uptake of nitrate. However, $Na^+$-gradient across the membrane was suggested to play a role in nitrate uptake since monensin which collapses $Na^+$-gradient strongly inhibited nitrate uptake. Exogenously added glucose and lactate stimulated nitrate uptake in the starved cells. N, N'-dicyclohexylcarbodiimide, an inhibitor of ATPase, could also inhibit nitrate uptake suggesting that ATP hydrolysis was required for nitrate uptake. All these results indicate that nitrate uptake in A. halophytica is ATP-dependent, driven by ${\Delta}pH$ and $Na^+$-gradient.

• Biomedical Science Letters
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• v.15 no.4
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• pp.287-293
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• 2009

Phospholipase D (PLD) is an enzyme hydrolyzing phosphatidylcholine to phosphatidic acid (PA) and choline. We investigated the involvement of PLD1 in the uptake of norepinephrine (NE) in PC12 cells, pheochromocytoma cells. NE uptake was specific in PC12 cells because nomifensine, a specific blocker of NE transporter, blocked NE uptake. Inhibition of PLD function in PC12 cells by the treatment of butanol suppressed the NE uptake. In contrast, overexpression of PLD1 in PC12 cells increased NE uptake efficiently. These results suggest that PLD activity is involved in NE uptake. We explored the action mechanism of PLD in NE uptake. PA phosphatase inhibitor, propranolol, blocks the formation of PKC activator diacylglycerol from PA. Propranolol treatment to PC12 cells blocked dramatically the uptake of NE. Specific PKC inhibitors, GF109203X and Ro31-8220, blocked NE uptake. Taken together, we suggest for the first time that PLD1 activity is involved in NE uptake via the activation of PKC.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.2
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• pp.137-146
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• 1999

Interactions among dexamethasone, dehydroepiandrosterone (DHEA), lipopolysaccharide (LPS), and antimycin A on the glutamate uptake and the polyamine uptake were investigated in primary cultures of rat cerebral cortical astrocytes to examine the effects of dexamethasone and DHEA on the regulatory role of astrocytes in conditions of increased extracellular concentrations of glutamate or polyamines. 1. $[^3H]Glutamate$ uptake: LPS and antimycin A decreased $V_{max},$ but both drugs had little effect on $K_m.$ Dexamethasone also decreased basal $V_{max}$ without any significant effect on $K_m.$ And dexamethasone further decreased the antimycin A-induced decrease of $V_{max}.$ DHEA did not affect the kinetics of basal glutamate uptake and the change by LPS or antimycin A. 2. $[^{14}C]Putrescine$ uptake: LPS increased $V_{max},$ and antimycin A decreased $V_{max}.$ They showed little effect on $K_m.$ Dexamethasone decreased $V_{max}$ of basal uptake and further decreased the antimycin A-induced decrease of $V_{max},$ and also decreased $V_{max}$ to less than control in LPS-treated astrocytes. DHEA did not affect $K_m$ and the change of $V_{max}$ by LPS or antimycin A. 3. $[^{14}C]Spermine$ uptake: Antimycin A decreased $V_{max},$ and LPS might increase $V_{max}.\;K_m$ was little affected by the drugs. Dexamethasone decreased basal $V_{max}$ and might further decrease the antimycin A-induced decrease of $V_{max}.$ And dexamethasone also decreased $V_{max}$ to less than control in LPS-treated astrocytes. DHEA might increase basal $V_{max}$ and $V_{max}$ of LPS-treated astrocytes. 4. $V_{max}$ of glutamate uptake by astrocytes was increased by putrescine (1000 ${\mu}M$ & 2000 ${\mu}M$) and spermidine (200 ${\mu}M,$ 500 ${\mu}M$ & 2000 ${\mu}M$). Spermine, 200 ${\mu}M$ (and 100 ${\mu}M$), also increased $V_{max},$ but a higher dose of 2000 ${\mu}M$ decreased $V_{max}.\;K_m$ of glutamate uptake was not significantly changed by these polyamines, except that higher doses of spermine showed tendency to decrease $K_m$ of glutamate uptake. In astrocytes, dexamethasone inhibited the glutamate uptake and the polyamine uptake in normal or hypoxic conditions, and the polyamine uptake might be stimulated by LPS and DHEA. Polyamines could aid astrocytes to uptake glutamate.

• Preventive Nutrition and Food Science
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• v.10 no.1
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• pp.52-57
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• 2005

Soy and soy foods are a rich source of isoflavones, which possess several biological activities. The effect of soy isoflavones, genistin and diadzin and their respective aglycones, on glucose uptake in adipocytes isolated from normal or high-fat fed rats was examined. As expected, insulin stimulated glucose uptake in a concentration-dependent manner. However, genistin and daidzin and their aglycones inhibited glucose uptake in a concentration-dependent (25-100μM) manner. In a time-course response, the aglycones significantly inhibited glucose uptake throughout 3 hr (after 30, 60, 120, 180 min), whereas the glycones only significantly inhibited the glucose uptake after 120 min and 180 min in the isolated rat adipocytes. Thus, the glucosides of genistein and daidzein, i.e. genistin and daidzin, were much less effective in inhibiting glucose uptake than their aglycones. In addition, genistin and daidzin did not significantly affect the insulin-stimulated glucose uptake, whereas genistein and daidzein did significantly inhibited glucose uptake compared to the vehicle control group by 47.5% and 24.8%, respectively (p < 0.05). The isoflavones also significantly inhibited glucose uptake in adipocytes isolated from rats fed a high-fat diet (50% of total calorie intake) when compared to the vehicle control. Finally, the isoflavones were found to enhance lipolysis in adipocytes isolated from high-fat fed rats, where the glycerol released by the aglycones was also higher than that released by the glycones. The current results showed that the inhibitory effect of daidzein on glucose uptake was very similar to that of genistein. The aglycones were more potent in inhibiting the uptake of glucose and a more potent stimulator of lypolysis than the glycones in adipocytes isolated from high-fat fed rats.

• Journal of Pharmaceutical Investigation
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• v.20 no.4
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• pp.179-191
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• 1990

A central dogma of pharmacology is that only unbound drug is capable of translocation across biological membrane. Thus, hepatic uptake is assumed to be solely determined by the unbound concentration of the diffusible moiety at the surface of the liver cell. However, an increasing number of experimental observations with xenobiotics that are normally very extensively bound to plasma proteins (>99%) appear to be inconsistent with these assumptions. This suggested that in addition to progressive spontaneous dissociation within the liver sinusoids and space of Disse, direct interactions of the albumin-drug complex at the plasma membrane may facilitate dissociation of the complex. To explain this phenomena. called albumin-mediated uptake, 4 mechanisms have been suggested. The validity of such hypotheses needs to be examined by the further study. Because albumin-mediated uptake has also been observed to occur in other plasma proteins, protein-mediated uptake rather than albumin-mediated uptake seems to be acceptable.

• Molecular & Cellular Toxicology
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• v.3 no.3
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• pp.198-207
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• 2007

[ $^{18}F$ ]-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) scan has been found to reflect tumor aggressiveness and prognosis in various types of cancer. In this study, the gene expression profiles of glial tumors were evaluated to determine whether glial tumors with high $^{18}F$-FDG uptake have more aggressive biological potential than with low uptake. Surgical specimens were obtained from the 12 patients with glial tumors (4 males and 8 females, age range 42-68 years). The tumor samples were divided into two groups based on the $^{18}F$-FDG uptake PET scan findings: high $^{18}F$-FDG uptake (n=4) and low $^{18}F$-FDG uptake (n=8). The pathological tumor grade was closely correlated with the $^{18}F$-FDG uptake pattern: Glial tumors with high $^{18}F$-FDG uptake were pathologically Edmondson-Steiner grade III, while those with low uptake were grade II. The total RNA was extracted from the frozen tissues of all glial tumors (n=12), and adjacent non-cancerous tissue (n=3). The gene expression profiles were evaluated using cDNA microarray. The glial tumors with high $^{18}F$-FDG uptake showed increase expression of 15 genes compared to those with low uptake (P<0.005). Nine genes were down-regulated. Gene expression is closely related to cell survival, cell-to-cell adhesion or cell spreading; therefore, glial tumors with high $^{18}F$-FDG uptake appear to have more aggressive biological properties than those with low uptake.

• The Korean Journal of Nuclear Medicine
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• v.16 no.2
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• pp.49-58
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• 1982

Renal transplant uptake of $^{99m}Tc-tin$ colloid was evaluated in 26 patients. Seventy-seven examinations were performed comparing transplant with bone marrow activity, clinical and/or pathological diagnosis. There were 13 instances of acute rejection; 7 of these exhibited slight uptake of radiocolloid in the renal transplant, 1 had marked uptake, and 5 had no evidence of uptake. There were 7 instances of chronic rejection; 5 of which demonstrated marked transplant uptake of radiocolloid, 1 had slight uptake, and 1 had no evidence of uptake. There were 2 instances of acute tubular necrosis and 55 instances of normal transplant function, but none of these exhibited transplant uptake of radiocolloid. From the result, the uptake of $^{99m}Tc-tin$ colloid by renal transplant appears to signal rejection as long. as the vascular supply is not severely compromised. Acute rejection may be represented by slight radiocolloid uptake, and chronic rejection by marked uptake when compared to bone marrow activity.

• Journal of Pharmaceutical Investigation
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• v.21 no.1
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• pp.43-50
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• 1991

The hepatic uptake of an anionic fluorescence probe, l-anilino-8-naphthalene sulfonate (ANS) was characterized using isolated rat hepatocytes. The initial uptake rate of ANS by isolated hepatocytes was determined. The uptake process of ANS was fitted well to the Michaelis-Menten equation with a saturable component. The $V_{max}$ and $K_m$ values were $2.9{\pm}0.1\;nmol/min/mg$ protein and $29.1{\pm}3.2\;{\mu}M$, respectively. The uptake clearance $(CL_{up})$ based on the ratio of $V_{max}$ to $K_m$ was 11.7 ml/min/g liver, revealing the good coincidence with that assessed from the analysis of the plasma disappearance curve in previous report. Furthermore, the effect of serum protein on the hepatic uptake of ANS into isolated hepatocytes was investigated. The permeability clearances $(PS_{inf})$ of ANS uptake were much higher than those predicted based on the unbound fractions in the presence of serum. These suggested that the hepatic uptake of extensively serum protein-bound ANS is mediated not only by the unbound form of ligand but also by the serum protein-mediated uptake mechanism.

• Animal cells and systems
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• v.14 no.4
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• pp.245-252
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• 2010

Iron uptake in mitochondria and fractionated mitochondria compartments was studied to understand iron transport in heart mitochondria. The inner membrane is most active in iron uptake. Mitochondrial uptake was dependent on iron concentration and the amount of mitochondria. Iron transport was inversely proportional to pH in the range of 6.0 to 8.0. Iron transport reached a maximum after 30 min of incubation at $37^{\circ}C$. Iron uptake was inhibited by 1 mM ATP and stimulated by 1 mM ADP. The oxidative phosphorylation inhibitor oligomycin inhibited iron uptake, but rotenone and antimycin A did not. The divalent ions $Mg^{2+}$, $Cu^{2+}$, $Mn^{2+}$, and $Zn^{2+}$ suppressed iron uptake at $10\;{\mu}M$ and stimulated it at 1 mM. The divalent ion $Ca^{2+}$ stimulated iron uptake at $10\;{\mu}M$ and suppressed it at 1 mM, competing with iron. The uptake of calcium was stimulated by 10 to $1000\;{\mu}M$ ATP, while iron uptake was stimulated reciprocally by 10 to $1000\;{\mu}M$ ADP, suggesting that these ions have movements similar to those of ATP and ADP.