Aims
The F1S and A genetic variants of α
1
‐acid glycoprotein (AAG) change under various physiological and pathological conditions. They also vary in their drug binding abilities. We have studied ...the stereoselective binding ability of each of the AAG variants using enantiomers of disopyramide (DP) and warfarin (WR).
Methods
The AAG variants were separated by hydroxyapatite chromatography. Binding of drug enantiomers to the AAG variants was studied by the Hummel–Dreyer method. The characteristics of the binding activities were examined by Scatchard plot analysis. The first five amino‐terminal amino acids (residues 112–116) of the cyanogen bromide (CNBr) fragment (residues 112–181) of each of the separated AAG fractions were elucidated by Edman degradation.
Results
Commercial AAG was separated into two main fractions. Residues 112–116 of fraction 2 were identical to the amino acid sequences predicted from the AAG A gene, LAFDV, and encode the F1S variant. In fraction 3, the deduced amino acid sequence of the AAG B gene, FGSYL, was established, and encodes the A variant. The binding affinities of both DP enantiomers in fraction 3 were significantly higher than those in fraction 2. The differences between dissociation constants (Kd) in fractions 2 and 3 were 5.2‐fold for (S)‐DP (
P
< 0.05) and 3.7‐fold for (R)‐DP (
P
< 0.001). The dissociation constant of (S)‐DP (0.39 ± 0.08 µ
m
) was lower than that of (R)‐DP (0.53 ± 0.10 µ
m
) in fraction 3 95% confidence interval (CI) − 0.282, − 0.010;
P
< 0.05, although the binding activities of the DP enantiomers were almost the same in fraction 2. By contrast WR enantiomers had a higher binding affinity in fraction 2 than in fraction 3, the differences in dissociation constants between fractions 2 and 3 being 12.6‐fold for (S)‐WR (
P
< 0.001) and 8.3‐fold for (R)‐WR (
P
< 0.001). The dissociation constant of (S)‐WR (0.28 ± 0.10 µ
m
) was significantly lower than that of (R)‐WR (0.48 ± 0.08 µ
m
) in fraction 2 (95% CI − 0.369, − 0.028;
P
< 0.05), but there were no significant differences between the binding activities of WR enantiomers in fraction 3.
Conclusions
DP and WR enantiomers bind preferentially to fraction 3 and fraction 2, respectively. Fractions 2 and 3 are encoded by the AAG A and the AAG B genes, respectively.
A new MOS technology is developed for submicrometer MOS devices. In this new technology, TiSi 2 is formed on the source and drain diffused layers by self-aligned silicidation to reduce the sheet ...resistance, and TiN is formed in the contact holes by self-aligned nitridation of TiSi 2 . This TiN can be used as an effective barrier metal between Al and Si. TiSi 2 is prepared by a two-step annealing method to prevent a reaction between Ti and the field oxide. PSG cap annealing after TiSi 2 formation provides excellent p-n junction characteristics and relatively low silicide sheet resistance of 4 ω/□ even after annealing at 950°C for 30 min. TiN is formed by direct thermal nitridation of TiSi 2 in N 2 ambient at a temperature higher than 900°C after contact hole formation. The formation of TiN is confirmed by AES, ESCA, and X-ray diffraction analysis. The TiN formed by direct thermal nitridation is found to prevent Al diffusion into the Si substrate even for post-metallization annealing at 500°C for 1 h. The characteristics of devices fabricated by this new technology also are determined.
A scanning capacitance microscope (SCM) has been implemented by fabricating a contact-mode atomic force microscope (AFM) with a high-sensitive capacitance sensor. The SCM has promise as ...next-generation characterization technique of electrical properties such as interface traps in metal-oxide-semiconductor (MOS) devices and carrier density because the measurement is inherently two dimensional with high spatial resolution at a nanometer scale. We demonstrate differential capacitance and capacitance images of the p-n junction on a Si wafer induced by different dopant density. Also we show SCM images due to negatively trapped charges in a SiO2 film, which are injected from the conductive probe tip. The resulting shift in differential capacitance (dC/dV) versus voltage (V) curves due to the locally trapped charge was measured by the high-frequency dC/dV-V measurement. Finally, we applied the SCM to characterization of a cross-sectional surface of a silicon-on-insulator (SOI) wafer. The SCM images identified the depletion layer at the SOI/buried oxide (BOX) interface, and the thickness of the depletion layer was found to vary according to the bias voltage applied to the Si substrate. These results represent that the SCM is a promising tool for sub-micron-scale electrical characterization of not only a bulk Si wafer but also a SOI wafer.
Cross-sectioned silicon-on-insulator (SOI) wafers were examined by a combination of scanning probe techniques, namely scanning capacitance microscopy (SCM), scanning resistance microscopy (SRM) and ...Kelvin probe force microscopy (KFM). Tests were conducted using bonded SOI and separation by implanted oxygen (SIMOX) wafers. SCM images identified the depletion layer at the SOI–buried-oxide (BOX) interface, and the thickness of the depletion layer was found to vary according to the bias voltage applied to the Si substrate. SRM images identified the high-resistance region in the SOI wafers, and KFM resolved the charge distribution, revealing that SOI wafers hold inherent positive charge. The locations of positive charge accumulation were found to differ between the two types of SOI wafers. Based on the results of this study, the use of multiple scanning probe techniques represents a promising tool for sub-micron-scale electrical characterization of SOI wafers.
: In adult‐to‐adult living donor liver transplantation (LDLT), the graft volume is inevitably much smaller than the ideal liver mass (standard liver volume) for the recipient's metabolic demand. ...Patients with small‐for‐size grafts are treated with continuous venovenous haemodiafiltration (CVVHD) for the artificial liver support. However, little is known about the influence of CVVHD on the elimination of tacrolimus. The objective of this study was to elucidate the effect of CVVHD on the pharmacokinetics of tacrolimus in recipients of LDLT with small‐for‐size grafts. Three liver transplant recipients (one male and two females) and donors (two males and one female) were enrolled in this study. Blood samples from inflow port and outflow port were obtained on the first day at the start of CVVHD. Whole‐blood concentrations of tacrolimus were measured immediately using the microparticle enzyme immunoassay (MEIA; Abbott Laboratories). There was no significant difference between concentrations of tacrolimus in blood sampled at inflow port and outflow port sites and t1/2‐values of tacrolimus in the three recipients were 29.9, 63.6 and 28.8 h. CVVHD did not cause a decrease in the blood tacrolimus concentration. Adjustment to the dose or dosing interval is not required for patients treated with tacrolimus during CVVHD.
: The urinary ratio of 6β‐hydroxycortisol to cortisol (6β‐OHF/F) is considered to be the simplest and most practical method for estimation of hepatic cytochrome P450 3A4 (CYP3A4) activity as a ...non‐invasive marker of human in vivo CYP3A4 activity. However, the inter‐ and intra‐individual variability of the urinary 6β‐OHF/F ratio during liver regeneration and the effect of variability on optimal dose of tacrolimus have not yet been clarified. The objective of this study was to clarify the change in the urinary 6β‐OHF/F ratio during liver regeneration and to determine the effect of the liver graft function on the optimal tacrolimus dose in liver transplant recipients. Two liver transplant recipients (one male and one female) and eight healthy volunteers (five males and three females) were enrolled in this study. Urine samples were collected from the recipients from 08.00 hours for 24 h on post‐transplant period, 1–10 and 21–30 days postoperatively. In the healthy volunteers, morning spot urine samples were collected at 08.00 hours. The mean urinary 6β‐OHF/F ratio in the immediate postoperative period was significantly low (p < 0.05). However, a marked difference in the regulation of CYP3A4 activity during liver regeneration was found in the two recipients. A significant correlation was found between the urinary 6β‐OHF/F ratio and the C/D ratio of tacrolimus (R = 0.658, p < 0.05). The urinary 6β‐OHF/F ratio is a useful probe for estimating the variability of CYP3A4 activity in liver transplant recipients in early postoperative phase. Future studies should evaluate the clinical usefulness of the urinary 6β‐OHF/F ratio as a predictor of tacrolimus pharmacokinetics in liver transplantation.
A novel charge pumping method without using MOS transistors is proposed for obtaining a spatial distribution of interface traps in an SOI wafer. The proposed method can be performed without ...fabrication processes for the source/drain of MOS transistors that are essential for conventional charge pumping methods. In this method, Schottky contacts are used instead of the normal source/drain diffused layer. The results demonstrate that the proposed method is effective in applying to SOI wafer inspection.
Objective: α^sub 1^-Acid glycoprotein (AAG) has three main genetic variants, F1, S, and A variants. There are few reports on the correlation between AAG variants and binding activity of drug ...enantiomers. We studied the differences between the binding characteristics of enantiomers of disopyramide (DP), which is a basic drug. The aim of this study was to elucidate the cause of the differences between the binding characteristics of DP enantiomers. Methods: The variants in human AAG were separated by hydroxyapatite chromatography. Binding of DP enantiomers to AAG variants was studied by the ultrafiltration method. The characteristics of the binding of DP enantiomers to total variants and each variant were examined by Scatchard analysis within a range of concentrations from 0.5 to 50.0 µg/ml. Results: The binding capacity of S-DP was significantly higher than that of R-DP in variant 3, although the binding capacities of DP enantiomers were almost the same in variant 2. On the other hand, the binding capacities for both S-DP and R-DP in variant 3 were significantly higher than those in variant 2. Furthermore, there was an almost 2.4-fold difference in the dissociation constant (K^sub d^) between S-DP and R-DP in variant 3, although no significant difference was observed in the number of binding sites (N). In variant 2 no significant differences between DP enantiomers were observed in either the dissociation constant or number of binding sites per molecule of AAG. On the other hand, significant differences between variants 2 and 3 in the dissociation constant for both S-DP and R-DP were observed. The differences in dissociation constant between variants 2 and 3 were 4.0-fold in S-DP and 1.7-fold in R-DP. Conclusion: The difference between the binding capacities of S-DP and R-DP is due to differences in the association of DP to variants 3-6, and the role of the variants 1 and 2 in the binding of drugs to AAG is minor.PUBLICATION ABSTRACT
alpha1-acid glycoprotein (AAG) has three main genetic variants, F1, S, and A variants. There are few reports on the correlation between AAG variants and binding activity of drug enantiomers. We ...studied the differences between the binding characteristics of enantiomers of disopyramide (DP), which is a basic drug. The aim of this study was to elucidate the cause of the differences between the binding characteristics of DP enantiomers.
The variants in human AAG were separated by hydroxyapatite chromatography. Binding of DP enantiomers to AAG variants was studied by the ultrafiltration method. The characteristics of the binding of DP enantiomers to total variants and each variant were examined by Scatchard analysis within a range of concentrations from 0.5 to 50.0 microg/ml.
The binding capacity of S-DP was significantly higher than that of R-DP in variant 3, although the binding capacities of DP enantiomers were almost the same in variant 2. On the other hand, the binding capacities for both S-DP and R-DP in variant 3 were significantly higher than those in variant 2. Furthermore, there was an almost 2.4-fold difference in the dissociation constant (Kd) between S-DP and R-DP in variant 3, although no significant difference was observed in the number of binding sites (N). In variant 2 no significant differences between DP enantiomers were observed in either the dissociation constant or number of binding sites per molecule of AAG. On the other hand, significant differences between variants 2 and 3 in the dissociation constant for both S-DP and R-DP were observed. The differences in dissociation constant between variants 2 and 3 were 4.0-fold in S-DP and 1.7-fold in R-DP.
The difference between the binding capacities of S-DP and R-DP is due to differences in the association of DP to variants 3-6, and the role of the variants 1 and 2 in the binding of drugs to AAG is minor.
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