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  • Articles  (25)
  • Korea  (7)
  • permeability  (7)
  • transport  (7)
  • Arabidopsis thaliana  (5)
  • Springer  (25)
  • American Geophysical Union (AGU)
  • 1
    Electronic Resource
    Electronic Resource
    Prevalence of human foamy virus-related sequences in the Korean population (1998)
    Springer
    Journal of biomedical science 5 (1998), S. 267-273 
    Details
    ISSN: 1423-0127
    Keywords: Grave's disease ; Human foamy virus ; Korea ; Molecular epidemiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The possible association of human foamy virus (HFV) with human thyroid disorders such as Graves' disease (GD) has been a topic of controversy due to the inconsistent results reported by several groups of investigators. Here we report the investigation of the presence of HFV-related sequences in the Korean population. DNA was obtained from peripheral blood lymphocytes from 24 GD patients and 23 healthy blood donors and subjected to PCR amplification using three sets of nested primers derived fromgag, env, and LTR regions of the HFV genome. Contrary to previously reported studies, our analysis identified HFV-related sequences in the genomes of both healthy individuals and the GD patients. However, the nature of the HFV genome present in each group appeared to be different. We detected all 3 regions of HFV-related sequences in 29% of the HFV-positive GD patients, while no samples in the control group amplified all three regions. This suggests that the LTR may be used as a tool for screening for HFV in GD patients. Our data favor the hypothesis of a relationship between GD and the presence of HFV-related sequences, though in a complex way.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02255858
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluation of a Human Bio-Engineered Skin Equivalent for Drug Permeation Studies (2000)
    Springer
    Pharmaceutical research 17 (2000), S. 1092-1097 
    Details
    ISSN: 1573-904X
    Keywords: drug delivery systems ; skin alternatives ; transdermal drug delivery ; permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To test the barrier function of a bio-engineered human skin (BHS) using three model drugs (caffeine, hydrocortisone, and tamoxifen) in vitro. To investigate the lipid composition and microscopic structure of the BHS. Methods. The human skin substitute was composed of both epidermal and dermal layers, the latter having a bovine collagen matrix. The permeability of the BHS to three model drugs was compared to that obtained in other percutaneous testing models (human cadaver skin, hairless mouse skin, and EpiDerm™). Lipid analysis of the BHS was performed by high performance thin layered chromatrography. Histological evalulation of the BHS was performed using routine H&E staining. Results. The BHS mimicked human skin in terms of lipid composition, gross ultrastructure, and the formation of a stratum corneum. However, the permeability of the BHS to caffeine, hydrocortisone, and tamoxifen was 3-4 fold higher than that of human cadaver skin. Conclusions. In summary, the results indicate that the BHS may be an acceptable in vitro model for drug permeability testing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026405712870
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  • 3
    Electronic Resource
    Electronic Resource
    Metal contamination of soils and dusts in Seoul metropolitan city, Korea (1995)
    Springer
    Environmental geochemistry and health 17 (1995), S. 139-146 
    Details
    ISSN: 1573-2983
    Keywords: Metal contamination ; Seoul ; Korea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract To investigate the dispersion patterns and the characteristics of heavy metal contamination due to urbanisation and industrialisation, soils and dusts collected from the Seoul area were analysed for Cu, Pb, Zn and Cd. The metal concentrations in most soils and dusts are higher than the world averages. The pollution index ((Σ Metal concentrations in soils/Permissible level for metal)÷(Number of metals)) of soils and dusts is 〉 1 in most of the Seoul area, a result that concurs with the industrialisation and urbanisation index of the Seoul area. The soils are contaminated with Cu, Zn, Cd and particularly Pb. This suggests that the contamination of the soils in the Seoul area are mainly caused by vehicular emissions. The pollution index of soil is the highest in the Kuro area where Cu and Zn contamination in soils are due to the indigenous brass and bronze factories. From the discriminant analysis, the Seoul area may be partitioned into control, traffic and industrialized areas by the metal concentrations in the order of Zn 〉 Cu 〉 Pb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00126082
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis of Acyclic Polyethers Bearing Thioamide End-Groups and Selective Sensing of Silver Ion (1999)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 34 (1999), S. 321-330 
    Details
    ISSN: 1573-1111
    Keywords: polyether ; thioamides ; complexation ; ion selectivity ; transport ; thermodynamic parameter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A series of acyclic polyethers bearing thioamide end-groups and lipophilic alkyl chains were successfully synthesized with moderate yields. Transport measurements in a bulk liquid membrane (BLM) system indicated a very high selectivity of silver ion over other metal cations. Thermodynamic parameters (ΔH, TΔS, and log K) for ligand-metal ion complexations were determined by solution calorimetric titration in methanol at 25 °C. The complexations were enthalpy driven and silver ion exhibited a high selectivity over other metal ions due to the increase of covalent binding between the soft acid (Ag+) and soft base (sulfur).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008063902389
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  • 5
    Electronic Resource
    Electronic Resource
    A new model for impregnation mechanisms in different GF/PP commingled yarns (1994)
    Springer
    Applied composite materials 1 (1994), S. 351-371 
    Details
    ISSN: 1573-4897
    Keywords: commingled yarn ; impregnation ; consolidation ; thermoplastics ; processing ; permeability ; mechanical testing ; mathematical modelling ; compression moulding ; glass fibre bed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Impregnation mechanisms of different kinds of GF/PP commingled yarns have been studied. As the reinforcing fibres were always the same, a global description has been worked out. Two different mathematical approaches for fibre bed permeability (Kozeny-Carman and Gutowski) were compared. The constants of the applied mathematical models have to stay the same if the fibre reeinforcement and the fibre arrangement is the same. Neither the kind of matrix, nor the fibre volume content may change these constants. Differences in the degree of impregnation after the same process conditions can be only due to different sizes of fibre agglomerations, thus the initial distribution of reinforcing fibres and matrix. For an exact determination of impregnation times and conditions the exact distribution of fibres in the intermediate material and after processing has to be known. This distribution is determined by SEM microscopy and data given from the material supplier. The importance of different process parameters, such as temperature, pressure, processing time is weighted by determining the density and mechanical properties of the specimens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568041
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  • 6
    Electronic Resource
    Electronic Resource
    Two closely related cDNAs encoding starch branching enzyme from Arabidopsis thaliana (1996)
    Springer
    Plant molecular biology 30 (1996), S. 97-108 
    Details
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; cDNA ; gene expression ; starch biosynthesis ; starch branching enzyme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two starch branching enzyme (SBE) cDNAs were identified in an Arabidopsis seedling hypocotyl library using maize Sbe1 and Sbe2 cDNAs as probes. The two cDNAs have diverged 5′ and 3′ ends, but encode proteins which share 90% identity over an extensive region with 70% identity to maize SBE IIb [12]. Genomic Southern blots suggest that the two cDNAs are the products of single, independent genes, and that additional, more distantly related SBE genes may exist in the Arabidopsis genome. The two cDNAs hybridize to transcripts which show similar expression patterns in Arabidopsis vegetative and reproductive tissues, including seedlings, inflorescence rachis, mature leaves, and flowers. This is the first report of the identification of cDNAs encoding two closely related starch branching enzymes from the same species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00017805
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of phenobarbital andp-hydroxyphenobarbital glucuronide on acetaminophen metabolites in isolated rat hepatocytes: Use of a kinetic model to examine the rates of formation and egress (1993)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 21 (1993), S. 175-194 
    Details
    ISSN: 1573-8744
    Keywords: acetaminophen ; acetaminophen glucuronide ; biliary excretion ; p-hydroxyphenobarbital glucuronide ; isolated rat hepatocytes ; metabolism ; phenobarbital ; transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Conventional analysis of initial uptake and egress rates in isolated hepatocytes is limited in the ability to distinguish between rates of metabolite formation and egress, and to separate basolateral and canalicular transport processes. The present study examined the applicability of kinetic modeling in describing acetaminophen glucuronide (AG) and acetaminophen sulfate (AS) formation and egress in hepatocytes after acute exposure to phenobarbital or p-hydroxyphenobarbital glucuronide p-OHPBG) in vitro,or in vivophenobarbital pretreatment. A significant pretreatment effect on AG and AS disposition was seen based on initial rates of egress. In vivophenobarbital pretreatment decreased the initial egress rate of AG compared to vehicle pretreatment, and the initial egress rate of AS compared to all other treatments. A pharmacokinetic model incorporating AG and AS formation in hepatocytes as well as egress processes (including diffusional and active transport components) was fit to the data. Parameter estimates derived from model fits to the data showed the expected increase in acetaminophen glucuronidation and decrease in sulfation after phenobarbital pretreatment;in addition, an increase in the AG diffusional rate constant and a decrease in the AS diffusional rate constant was apparent. The excretion Vmax for AG was decreased statistically after acute phenobarbital exposure in vitro,and in vivophenobarbital pretreatment, with a concomitant statistical increase in the KmforAG excretion. In vitroacute p-OHPBG exposure also decreased significantly the excretion Vmax for AG. These data are consistent with the hypothesis that phenobarbitalimpaired biliary excretion of AG is a function of impaired canalicular transport due to the presence of p-OHPBG. They further suggest that the mechanism may not be simple competitive inhibition. This work demonstrates the utility of a kinetic modeling approach to differentiate metabolic and transport processes when analyzing data from isolated hepatocyte studies. Additional information may be gained that would not be apparent by conventional methods of analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01059769
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  • 8
    Electronic Resource
    Electronic Resource
    Development and Characterization of Rabbit Tracheal Epithelial Cell Monolayer Models for Drug Transport Studies (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1499-1505 
    Details
    ISSN: 1573-904X
    Keywords: tracheal epithelial cells ; air-interfaced culture ; ion transport ; drug transport ; permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The objective of this study was to investigate how culture conditions would affect the morphological, functional, and permeability characteristics of rabbit tracheal epithelial cell layers being considered for drug transport studies. Methods. Rabbit tracheocytes were isolated by protease treatment and plated onto collagen-treated permeable supports at 1.3 × 106 cells/cm2. After 24 hr, cell layers were cultured either air-interfaced (AIC) on their apical surface or under conventional liquid covered conditions (LCC). Results. Scanning electron microscopy revealed mature cilia in AIC cell layers and ciliated cells denuded of cilia in LCC cell layers. Compared with LCC, AIC cell layers (n = 20) achieved a significantly higher peak equivalent short-circuit current (74.1 ± 6.5 vs. 51.6 ± 3.4 µA/cm2), a higher potential difference (70.9 ± 2.8 vs. 60.5 ± 3.0 mV), and a lower peak transepithelial electrical resistance (1.1 ± 0.03 vs. 1.5 ± 0.02 kohms,cm2). About 70% of the short-circuit current in AIC was amiloride-sensitive whereas 〈10% was furosemide-sensitive, similar to that found in native tissue. The corresponding values in LCC were 50% and 46%. The permeability of both AIC and LCC to lipophilic solutes (dexamethasone and propranolol) was similar, whereas the permeability of hydrophilic solutes (mannitol, sucrose, and albuterol) in AIC was only half that in LCC. Conclusions. Given the striking similarity in morphological and functional characteristics of the AIC to those in the in vivo situation, the AIC is favored as an in vitro model for future drug transport studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016291522345
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  • 9
    Electronic Resource
    Electronic Resource
    Relations Between Stock Returns and Fundamental Variables: Evidence from a Segmented Market (1999)
    Springer
    Asia Pacific financial markets 6 (1999), S. 221-233 
    Details
    ISSN: 1573-6946
    Keywords: book-to-market ; explanatory factors ; Korea ; stock returns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract This study examines relations between stock returns and potential explanatory factors in Korea, an important and segmented emerging market. Our results show that Korean stock returns in general and returns on stocks listed in Section 1 in particular are significantly positively related to book-to-market, sales-price, and debt-equity ratios, but not significantly related to market value of equity. Returns on stocks listed in Section 2 are, however, negatively related to market value of equity and not significantly related to the other three variables. Among the variables investigated by us, book-to-market ratio has the greatest explanatory power for stock returns and it indicates superior returns for value stocks. Our findings strengthen the international evidence of the role of book-to-market ratio in explaining stock returns by demonstrating its significance even in the segmented Korean market.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010071921399
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  • 10
    Electronic Resource
    Electronic Resource
    Radiolabeling of Methylphosphonate and Phosphorothioate Oligonucleotides and Evaluation of Their Transport in Everted Rat Jejunum Sacs (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 817-824 
    Details
    ISSN: 1573-904X
    Keywords: antisense ; radiolabel ; transport ; gastrointestinal ; methylphosphonate ; phosphorothioate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The therapeutic use of antisense oligonucleotides will likely involve their administration over protracted periods of time. The oral route of drug dosing offers many advantages over other possible routes when chronic drug administration is necessary. However, little is known about the potential for oligonucleotide uptake from the gastrointestinal tract. This issue is addressed in the current work. Methods. We have developed a simple procedure for radiolabeling oligonucleotides by reductive alkylation with 14C-formaldehyde. We have utilized this approach, as well as 5′ addition of fluorophores, to prepare labeled methylphosphonate and phosphorothioate oligonucleotides for use in intestinal transport studies. An everted rat gut sac model was employed to compare the transport of oligonucleotides to that of model compounds whose permeation properties are better understood. Results. We demonstrate that both methylphosphonate and phosphorothioate oligonucleotides are passively transported across the intestinal epithelium, probably by a paracellular route. The rates of transport for both types of oligonucleotides were similar, and were significantly greater than that of the very high MW polymer blue dextran, but were lower than the transport rate of valproic acid, a low MW compound known to have high oral availability. Conclusions. A significant degree of permeation of oligonucleotides across the gastrointestinal epithelium does occur, but it is still unclear whether this is sufficient to permit effective oral administration of oligonucleotides as drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016296617434
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