In-Wha Kim

Lung‐specific delivery of paclitaxel by chitosan‐modified PLGA nanoparticles via transient formation of microaggregates

Chitosan-modified paclitaxel-loaded poly lactic-co-glycolic acid (PLGA) nanoparticles with a mean diameter of 200-300 nm in distilled water were prepared by a solvent evaporation method. The mean diameter increased dramatically in contact with the mouse (CDF(1)) plasma, as a function of chitosan concentration in the modification solution (e.g., 2670.5 nm for 0.7% chitosan-modified nanoparticles, NP(3)), but reverted to almost its original size (i.e., 350.7 nm for NP(3)) following 5 min of gentle agitation. The zeta potential of PLGA nanoparticles was changed to positive by the chitosan modification. The in vitro uptake into, and cytotoxicity of the nanoparticles against, a lung cancer cell line (A549) were significantly increased by the modification. Most importantly, a lung-specific increase in the distribution index of paclitaxel (i.e., AUC(lung)/AUC(plasma)) was observed for chitosan-modified nanoparticles (e.g., 99.9 for NP(3) vs. 5.4 for Taxol) when nanoparticles were administered to lung-metastasized mice via the tail vein at a paclitaxel dose of 10 mg/kg. Transient formation of aggregates in the blood stream followed by enhanced trapping in the lung capillaries, and electrical interaction-mediated enhanced uptake across the endothelial cells of the lung tumor capillary appear to be responsible for the lung-tumor-specific distribution of the chitosan modified nanoparticles.

Neutralization epitopes on the antigenic domain II of the Orientia tsutsugamushi 56-kDa protein revealed by monoclonal antibodies

Monoclonal antibodies (MoAbs) reactive with the authentic Orientia tsutsugamushi 56-kDa protein were generated. MoAb FS10 and FS15 showed in vitro, as well as, in vivo neutralizing activity upon O. tsutsugamushi infection. Deletion mutants of the gene for 56-kDa protein of O. tsutsugamushi Boryong were expressed to map the binding region. FS10 and FS15 are bound to amino acids (aa) located in an antigenic domain II, at residues 140-160 and 187-214, respectively. Computer modeling indicated that aa 146-153 were important for antigenicity against FS10. A sequence for aa 142-150 was highly homologous between oriential strains. These results suggest that the antigenic determinant for neutralizing MoAbs is an epitope within aa 140-160. Furthermore, this region may be important for the adhesion/invasion or intracellular survival of O. tsutsugamushi within host cells.

ABC Drug Transporters as Molecular Targets for the Prevention of Multidrug Resistance and Drug-Drug Interactions

ABC transporters play an important role in mediating the cytoplasmic concentration of endogenous and xenobiotic substances. They therefore influence the pharmacokinetic profile of a variety of drugs. By virtue of their localization to plasma membranes in the intestine, liver, blood-brain and other vital biological barriers, a majority of ABC drug transporters cause drug-drug interactions, decreased drug efficacy and multidrug resistance for chemotherapeutic agents. Thus, elucidating which drug entities are substrates for ABC drug transporters is a crucial step in the drug development and treatment process. Here, we review the current status of methodology used to categorize drug compounds as substrates or modulators for the major ABC drug transporters including ABCB1, ABCC1 and ABCG2.

Induction of neutralizing antibody in mice by immunization with recombinant 56 kDa protein of Orientia tsutsugamushi

Anti-oriential antibody inhibits Orientia tsutsugamushi attachment to, and penetration of, host cells. However, O. tsutsugamushi antigens that induce the production of a neutralizing antibody have not been identified. The authors immunized mice and rabbits with the recombinant 56 kDa protein of O. tsutsugamushi fused to the maltose binding protein of Escherichia coli (MBP-Bor56) and analysed their effect on O. tsutsugamushi attachment to or penetration of L929 cells. O. tsutsugamushi attachment and penetration were measured by using an indirect immunofluorescent antibody assay (IFA). O. tsutsugamushi growth in L929 cells was determined by [3H]thymidine uptake assay. By IFA, we observed a 96% reduction of attachment or penetration of O. tsutsugamushi treated with rabbit anti-MBP-Bor56 sera. [3H]thymidine uptake showed that mouse anti-MBP-Bor56 sera caused a 91% reduction in O. tsutsugamushi growth, when compared to mouse anti-MBP sera. These results suggest that the 56 kDa protein of O. tsutsugamushi plays an important role in O. tsutsugamushi attachment to or penetration of cells.

Physical evaluation of popped cereal snacks with spent hen meat

Various blends of spent hen meat and grains (potato starch, corn starch, and rice flour) were popped using a popping machine. Lowest bulk density was observed in the snack with 1:2 ratio of meat and potato starch. Except for the popped snack with meat and rice flour, as the starch content increased, bulk density decreased gradually. Popped snacks with grains only were higher in L* value than those with meat and grains. The a* and b* values increased with increasing meat content. All popped snacks were significantly different (P<0.001) in bulk density, color, and breaking force. As the grain content of snacks increased, the size of the air cells also increased. Results of scanning electron microscopic and optical microscopic observations revealed the popping degree of snack with starch and spent hen meat was affected by the presence of meat. The optimum ratios of meat to grain for high expansion ratio were determined to be 1:2 and 1:3 of meat to corn starch and potato starch.

Epigenetic changes in gene expression for drug-metabolizing enzymes and transporters.

Individual differences in drug response can be caused by genetic and epigenetic variability and disease determinants. Pharmacoepigenetics is a new field that studies the expression changes in pharmacogenes without changes in DNA sequences. Epigenetic control mechanisms are associated with DNA methylation, histone modification, small noncoding RNAs, and nucleosome remodeling. Researchers are actively attempting to identify epigenetic mechanisms for controlling the expression of enzymes and transporters affecting the metabolism and disposition of drugs. Current evidence suggests that epigenetic changes play a major role in cytochrome P450 enzyme expression, major transporter function, and in interactions with nuclear receptors. A thorough understanding of pharmacoepigenetics provides insight into new approaches to drug discovery and development, provides an understanding of previously observed actions of older drugs, and provides a pathway by which epigenetics can be harnessed to provide better patient‐specific therapy.

Simultaneous determination of loxoprofen and its diastereomeric alcohol metabolites in human plasma and urine by a simple HPLC-UV detection method

A simple, reliable HPLC-UV detection method was developed for the simultaneous determination of loxoprofen and its metabolites (i.e. trans- and cis-alcohol metabolites), in human plasma and urine samples. The method involves the addition of a ketoprofen (internal standard) solution in methanol, zinc sulfate solution and acetonitrile to plasma and urine samples, followed by centrifugation. An aliquot of the supernatant was evaporated to dryness, and the residue reconstituted in a mobile phase (acetonitrile:water=35:65 v/v, pH 3.0). An aliquot of the solution was then directly injected into the HPLC system. Separations were performed on octadecylsilica column (250x4.5 mm, 5 microm) with a guard column (3.2x1.5 cm, 7 microm) at ambient temperature. Loxoprofen and the metabolites in the eluent were monitored at 220 nm (a.u.f.s. 0.005). Coefficients of variations (CV%) and recoveries for loxoprofen and its metabolites were below 10 and over 96%, respectively, in the 200 approximately 15000 ng ml(-1) range for plasma and 500 approximately 50000 ng ml(-1) range for urine. Calibration curves for all the compounds in the plasma and urine were linear over the above-mentioned concentration ranges with a common correlation coefficient of 0.999. The detection limit of the present method was 100 ng for all the compounds. These results indicate that the present method is very simple and readily applicable to routine bioavailability studies of these compounds with an acceptable sensitivity.

Combined interaction of multi-locus genetic polymorphisms in cytarabine arabinoside metabolic pathway on clinical outcomes in adult acute myeloid leukaemia (AML) patients

Cytarabine arabinoside (ara-C) is the key agent for treating acute myeloid leukaemia (AML). Here, we genotyped 139 single nucleotide polymorphisms (SNPs) within the ara-C transport and metabolic pathway using the Illumina Golden Gate Assay in 97 patients with previously non-treated de novo AML other than M3. DCK rs4694362 (CC genotype) was a significant poor prognostic factor for overall survival (OS) (hazard ratio [HR], 33.202 [95% confidence interval (CI), 4.937-223.273], P<0.0001, P(Bonferroni)=0.017). SLC29A1 rs3734703 (AA or AC genotype) in combination with TYMS rs2612100 (AA genotype) was significantly associated with shorter relapse free survival (RFS) (HR, 17.630 [95% CI, 4.829-64.369], P<0.0001, P(Bonferroni)=0.021). These SNPs showed moderate or large inter ethnic divergence in allele frequencies from African or Caucasian populations. The results of our study suggest that a single SNP and SNP-SNP interactions may help to predict the drug response and provide a guide in developing individualised chemotherapy for AML patients receiving ara-C based chemotherapy.

ABCB1 C3435T Genetic Polymorphism on Population Pharmacokinetics of Methotrexate After Hematopoietic Stem Cell Transplantation in Korean Patients: A Prospective Analysis

BACKGROUND Methotrexate (MTX) is often used to prevent graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (HSCT). However, MTX has great pharmacokinetic variability and its use can result in fatal complications and/or infections after HSCT. OBJECTIVES The purposes of this study were to build a population pharmacokinetic model of MTX treatment in Korean patients who have undergone HSCT and to identify covariates, including genetic polymorphisms, that affect the pharmacokinetic properties of MTX. METHODS Clinical characteristics and MTX concentration data for 20 post-HSCT patients were collected. For each patient, ABCB1, ABCC2, ATIC, GGH, MTHFR, and TYMS genotyping was performed. Population pharmacokinetic analysis was performed using the NONMEM program. Analysis of MTX pharmacokinetic properties was accomplished using a 2-compartment pharmacokinetic model that incorporated first-order conditional estimation methods with interaction. The effects of a variety of demographic and genetic factors on MTX disposition were investigated. RESULTS The study population consisted of 12 men (60%) and 8 women (40%). Median age and body weight were 28 years (range, 18-49 years) and 55.6 kg (range, 44.8-80.8 kg), respectively. Within the study population, the estimated mean MTX clearance (CL) was 7.08 L/h, whereas the mean central compartment volume (V(1)) of MTX distribution was 19.4 L. MTX CL was significantly affected by glomerular filtration rate (GFR), penicillin use, and the ABCB1 3435 genotype. Interindividual variabilities for CL and V(1) were 21.6% and 73.3%. A 10-mL/min GFR increase was associated with a 32% increase in mean MTX CL, whereas penicillin use was associated with a decrease in MTX CL of 61%. MTX CL was significantly greater (by ∼21%) in patients with the ABCB1 3435 CC and CT genotype than in those with the ABCB1 3435 TT genotype (P < 0.001). CONCLUSIONS There was great interindividual variation in MTX pharmacokinetic properties in patients who had undergone HSCT. GFR, concurrent penicillin use, and the presence of the ABCB1 3435 C

Transmission of Scrub Typhus by Needlestick from a Patient Receiving Pefloxacin

A nurse experience a needlestick during the care of a patient with scrub typhus, treated with pefloxacin (400 mg twice daily) and cefazolin. Seven days after the needlestick, pain and erythematous swelling developed at the tip of her left fourth finger, the site of the needlestick. Fever and headache developed 10 days later, and her skin lesion became a small vesicle surrounded by a dark erythematous area. The diagnosis of scrub typhus was made by a rising indirect immunofluorescent antibody titre, and her illness was improved with doxycycline.