Experimental evidence of tunable space-charge-layer-induced electrical properties of nanocrystalline ceria thin films.

Fully dense nanocrystalline ceria films were successfully deposited on a MgO single crystal by pulsed laser deposition (PLD). The electrical conductivity of the nanocrystalline thin film was 20 times higher than that of the bulk sample. The activation energy of bulk ceria was 2.3 eV, whereas the activation energy of the nanocrystalline sample was only 1.2 eV. After post-annealing at 1273 K in which the grain size of the nanocrystalline thin film increased to ~400 nm, the electrical conductivity and activation energy of the film were changed similar to those of bulk. These unique electrical properties of the nano-crystalline thin-film can be attributed to the grain size effect, or more specifically, to the space charge layer (SCL) effect. Furthermore, the electrical conductivity of the nanocrystalline thin film became similar to that of the bulk in an extremely reducing atmosphere because of the unusual dependence of the SCL effect on the oxygen partial pressure.

'Illusional' nano-size effect due to artifacts of in-plane conductivity measurements of ultra-thin films.

The nano-size effect, which indicates a drastic increase in conductivity in solid electrolyte materials of nano-scale microstructures, has drawn substantial attention in various research fields including in the field of solid oxide fuel cells (SOFCs). However, especially in the cases of the conductivity of ultra-thin films measured in an in-plane configuration, it is highly possible that the 'apparent' conductivity increase originates from electrical current flowing through other conduction paths than the thin film. As a systematic study to interrogate those measurement artifacts, we report various sources of electrical current leaks regarding in-plane conductivity measurements, specifically insulators in the measurement set-up. We have observed a 'great conductivity increase' up to an order of magnitude at a very thin thickness of a single layer yttria-stabilized zirconia (YSZ) film in a set-up with an intentional artifact current flow source. Here we propose that the nano-size effect, reported to appear in ultra-thin single layer YSZ, can be a result of misinterpretation.

Expression of functional pentameric heat-labile enterotoxin B subunit of Escherichia coli in Saccharomyces cerevisiae.

Although the Escherichia coli heat-labile enterotoxin B subunit (LTB) has already been expressed in several different systems, including prokaryotic and eukaryotic organisms, studies regarding the synthesis of LTB into oligomeric structures of pentameric size in the budding yeast Saccharomyces cerevisiae have been limited. Therefore, this study used a functional signal peptide of the amylase 1A protein from rice to direct the yeast-expressed LTB towards the endoplasmic reticulum to oligomerize with the expected pentameric size. The expression and assembly of the recombinant LTB were confirmed in both the cell-free extract and culture media of the recombinant strain using a Western blot analysis. The binding of the LTB pentamers to intestinal epithelial cell membrane glycolipid receptors was further verified using a GM1-ganglioside enzyme-linked immunosorbent assay (GM1-ELISA). On the basis of the GM1-ELISA results, pentameric LTB proteins comprised approximately 0.5-2.0% of the total soluble proteins, and the maximum quantity of secreted LTB was estimated to be 3 mg/l after a 3-day cultivation period. Consequently, the synthesis of LTB monomers and their assembly into biologically active oligomers in a recombinant S. cerevisiae strain demonstrated the feasibility of using a GRAS microorganism-based adjuvant, as well as the development of carriers against mucosal disease.

Five-year report of national surveillance of antimicrobial resistance in Pseudomonas aeruginosa isolated from non-tertiary care hospitals in Korea (2002-2006).

A nationwide surveillance of the antimicrobial resistance of Pseudomonas aeruginosa isolates from non-tertiary care hospitals was conducted in Korea from 2002 to 2006. Resistance to almost all antimicrobial agents decreased significantly from 2003 (P < 0.01). Resistance rates to the major antipseudomonal agents, ceftazidime, imipenem, meropenem, and aztreonam, were 18.8%, 20.5%, 18.7%, and 19.7%, respectively, in 2003. However, they had all decreased to below 10% in 2006. The proportion of multidrug-resistant isolates that were resistant to at least 3 of 5 major antipseudomonal agent decreased from 33.5% in 2003 to 23.1% in 2006 (P < 0.05). In this study, we found a decreasing trend in resistance rates and low resistance rates in P. aeruginosa from non-tertiary care hospitals compared with those from general hospitals, including tertiary care hospitals, in Korea. Our data provide valuable information for the selection of reliable empiric therapies for P. aeruginosa infections in non-tertiary care hospital patients, including outpatients.

Pharmacokinetic and pharmacodynamic characteristics of a new S-amlodipine formulation in healthy Korean male subjects: a randomized, open-label, two-period, comparative, crossover study.

BACKGROUND: Amlodipine, a dihydropyridine calcium channel antagonist, is prescribed for the management of angina and hypertension. It is used therapeutically as a racemic mixture, composed of S- and R-enantiomers, but its calcium channel-blocking effect is confined to S-amlodipine; R-amlodipine has 1000-fold less activity than its S-enantiomer. OBJECTIVE: The objective of this study was to compare the pharmacokinetic and pharmacodynamic properties and safety profiles of a newly developed amlodipine formulation, composed wholly of S-amlodipine, with those of the conventionally prescribed racemic formulation. METHODS: This randomized, open-label, 2-period, comparative, crossover study was conducted with healthy volunteers at the Gil Medical Center and Gachon Medical School, Incheon, Korea. Male subjects, aged 20 to 50 years, were eligible to participate if their weight was within 20% of ideal body weight and if they were judged by physicians to be healthy. All subjects were randomly assigned in a 1:1 ratio to 1 of 2 treatment sequences: (1) a single dose of the test amlodipine formulation (S-enantiomer amlodipine 5 mg p.o.) (Lodien [Hanlim Pharmaceutical Co., Seoul, Korea]) in the first study period, followed by a single dose of the reference amlodipine formulation (racemate 10 mg p.o.) (Norvasc [Pfizer Pharmaceuticals Korea Ltd., Seoul, Korea]) in the second study period, or (2) a single dose of the reference formulation in the first study period, followed by a single dose of the test formulation in the second period. A 3-week washout occurred between study periods. Blood samples for pharmacokinetic analysis of S-amlodipine were collected at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 24, 48, 72, 96, 120, 144, and 168 hours after drug administration. Pharmacodynamic variables (ie, systolic and diastolic blood pressure and heart rate) were measured at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 24, 48, and 72 hours after administration. Safety profiles were also assessed. Hematology, biochemistry, electrocardiography, and urinalysis were performed at baseline and end of study. Adverse events were monitored throughout the study period. Pharmacokinetic characteristics were compared using noncompartmental analysis. Pharmacokinetic equivalence was concluded if the geometric mean ratios of the plasma Cmax and AUC were within the predetermined range of 80% to 125%. RESULTS: Twenty-six healthy Korean male volunteers were screened and 18 subjects (mean [SD] age, 23.4 [1.5] years [range, 21-26 years]; mean [SD] weight, 69.3 [6.8] kg [range, 60-88 kg]) were enrolled and completed the study. The plasma concentration-time profiles of S-amlodipine were comparable after administration of both formulations. The mean (SD) values for Cmax AUC from time 0 to the last available measurement (AUC(last)), and AUC from 0 to infinity (AUC(0-infinity)) for the reference formulation (3.0 [0.6] ng/mL, 151.4 [35.7] ng x h/mL, and 175.3 [45.1] ng x h/mL, respectively) did not differ significantly from those for the test formulation (3.1 [0.6] ng/mL, 139.7 [40.3] ng x h/mL, and 161.7 [43.8] ng x h/mL, respectively). The calculated 90% Cls for the corresponding ratios of log-transformed Cmax, AUCO(0-infinity), and AUC(last) were 97.56% to 112.51%, 86.31% to 98.74%, and 83.46% to 100.04%, respectively, which met the predetermined criteria for pharmacokinetic equivalence. Despite the single administration, significant changes in maximal blood pressure and heart rate were observed after drug administration for both formulations, compared with baseline values (all, P < 0.001). However, no significant differences were observed between the 2 formulations in terms of pharmacodynamic profiles, and no clinically relevant changes were observed for either formulation with respect to physical examination, hematology, biochemistry, electrocardiography, or urinalysis. Neither formulation caused any serious adverse events. CONCLUSIONS: Two amlodipine formulations were found to be equivalent in terms of the pharmacokinetics of S-amlodipine. The newly developed formulation, comprised of only S-amlodipine, had pharmacodynamic profiles comparable to those of the conventional racemic amlodipine formulation in these healthy Korean male subjects. Both formulations were well tolerated.

Screening of newborns and high-risk group of children for inborn metabolic disorders using tandem mass spectrometry in South Korea: a three-year report.

BACKGROUND: Mass screening using tandem mass spectrometry(MS/MS) was initiated to determine if the incidence of metabolic disorder is sufficiently high to meet the criteria for newborn screening, and whether or not early medical intervention might be beneficial to the patients. METHODS: Newborns and children in a high-risk group were screened using MS/MS from April 2001 to March 2004. Blood spots of newborns were collected between 48 and 72 h after birth. The dried blood spots was extracted with 150 microl of methanol, and analyzed by MS/MS. RESULTS: From April 2001 to March 2004, 79,179 newborns were screened for organic, amino and fatty acid metabolism disorders, which account for approximately 5.4% of annual births in South Korea. Twenty-eight newborns were diagnosed with one of the metabolic disorders and the collective estimated prevalence amounted to 1 in 2800 with a sensitivity of 97.67%, a specificity of 99.28%, a recall rate of 0.05%, and a positive predictive value of 6.38%. 6795 infants/children at high risk were screened and 20 were confirmed to have metabolic disorders. CONCLUSION: The collective total prevalence of 1:2800 in newborns indicates an underestimation of the incidence of metabolic disorders prior to implementing MS/MS screening in South Korea.

Determination of phloroglucinol in human plasma by high-performance liquid chromatography-mass spectrometry.

A sensitive and selective liquid chromatographic method coupled with mass spectrometry (LC-MS) was developed for the quantification of phloroglucinol in human plasma. Resorcinol was used as internal standard, with plasma samples extracted using ethyl acetate. A centrifuged upper layer was then evaporated and reconstituted with mobile phase. The reconstituted samples were injected into a C(18) XTerra MS column (2.1 x 100 mm) with 3.5-microm particle size. The analytical column lasted for at least 500 injections. The mobile phase was 15% acetonitrile (pH 3.0), with flow-rate at 200 microl/min. The mass spectrometer was operated in negative ion mode with selective ion monitoring (SIM). Phloroglucinol was detected without severe interferences from plasma matrix when used negative ion mode. Phloroglucinol produced a parent molecule ([M-H](-)) at m/z 125 in negative ion mode. Detection of phloroglucinol in human plasma was accurate and precise, with quantification limit at 5 ng/ml. This method has been successfully applied to a study of phloroglucinol in human specimens.

Determination of ambroxol in human plasma using LC-MS/MS.

A sensitive and selective liquid chromatographic method coupled with tandem mass spectrometry (LC-MS/MS) was developed for the quantification of ambroxol in human plasma. Domperidone was used as internal standard, with plasma samples extracted using diethyl ether under basic condition. A centrifuged upper layer was then evaporated and reconstituted with 200 microl methanol. The reconstituted samples were injected into a C(18) XTerra MS column (2.1 x 30 mm) with 3.5 microm particle size. The analytical column lasted for at least 600 injections. The mobile phase was composed of 20 mM ammonium acetate in 90% acetonitrile (pH 8.8), with flow rate at 250 microl/min. The mass spectrometer was operated in positive ion mode using turbo electrospray ionization. Nitrogen was used as the nebulizer, curtain, collision, and auxiliary gases. Using MS/MS with multiple reaction monitoring (MRM) mode, ambroxol was detected without severe interferences from plasma matrix. Ambroxol produced a protonated precursor ion ([M+H](+)) at m/z 379 and a corresponding product ion at m/z 264. And internal standard (domperidone) produced a protonated precursor ion ([M+H](+)) at m/z 426 and a corresponding product ion at m/z 174. Detection of ambroxol in human plasma was accurate and precise, with quantification limit at 0.2 ng/ml. This method has been successfully applied to a study of ambroxol in human specimens.

Sensitive determination of erdosteine in human plasma by use of automated 96-well solid-phase extraction and LC-MS/MS.

A sensitive and selective method for quantitation of erdosteine in human plasma was established by use of 96-well solid-phase extraction (SPE) and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI/MS/MS). Plasma samples were transferred into 96-well OASIS HLB extraction plate using an automated sample handling system and the drugs were eluted with methanol. The eluents were then evaporated and reconstituted with mobile phase. All sample transfer and SPE was automated through the application of both the Perkin-Elmer MultiPROBE II HT and TOMTEC Quadra 96 workstation. Compounds were separated on a C18 column with 1 mM ammonium acetate-acetonitrile (80:20, pH 3.2), as mobile phase at a flow rate of 0.3 ml/min. The limit of quantitation (LOQ) was 0.2 ng/ml, using a sample volume of 0.2 ml for the analysis. The reproducibility of the method was evaluated by analyzing three at 14 quality control (QC) levels over the nominal concentration range from 0.2 to 5000 ng/ml. The intraday accuracy was found to range from 99.6 to 105.0% with precision (% RSD) of less than 4.76% at five QC levels. The interday accuracy was found to range from 95.0 to 100.5% with precision of less than 5.26% at five QC levels. Erdosteine produced a protonated precursor ion ([M+H]+) at m/z 250, and a corresponding product ion at m/z 204. Internal standard (letosteine) produced a protonated precursor ion ([M+H]+) at m/z 280 and a corresponding product ion at m/z 160. The high sample throughput of the method has been successfully applied to a pharmacokinetic study of erdosteine in human plasma.

Tandem mass spectrometric analysis for disorders in amino, organic and fatty acid metabolism: two year experience in South Korea.

Seoul Clinical Laboratories began screening newborns and high risk group blood spots with tandem mass spectrometry (MS/MS) in April 2001. The goal was to determine approximate prevalence of metabolic disorders and optimization of decision criteria for estimation of preventive effect with early diagnosis. Approximately 44,300 neonates and children were screened and the estimated prevalence (newborn/high risk group), sensitivity, specificity and recall rate amounted to 1:2000 / 1:1250, 94.1 %, 99.7 %, and 0.04 %, respectively. Confirmed 35 multiple metabolic disorders (newborn/high risk) were as follows; 16 amino acid disorders [classical PKU(3/4), BH4 deficient-hyperphenylalaninemia(0/1), Citrullinemia(2/0), Homocystinuria(0/2), Hypermethioninemia(0/1), Tyrosinemia(1/0)], OTC deficiency (0/1), MSUD (2/0), 10 organic acidurias [Propionic aciduria(2/1), Methylmalonic aciduria(0/1), Isovaleric aciduria(2/1), 3-methylcrotonylglycineuria(1/0), Glutaric aciduria type 1(2/0)], 9 fatty acid oxidation disorders [LCHAD def. (2/2), Mitochondrial TFP def.(0/1), VLCAD def.(1/0), LC3KT def.(0/1), SCAD def (1/0), MADD def (0/1). The relatively normal development of 15 patients with metabolic disorders among newborns (except for the expired) demonstrates the usefulness of newborn screening by MS/MS for early diagnosis and medical intervention. However, close coordination between the MS/MS screening laboratory and the metabolic clinic/biochemical geneticists is needed to determine proper decision of screening parameters, confirmation diagnosis, follow-up scheme and additional tests.

Surgical impact on serum anti-Müllerian hormone in women with benign ovarian cyst: A prospective study.

OBJECTIVE: The aim of this study was to evaluate the surgical impact of benign ovarian mass on ovarian reserve as measured by serum follicle stimulating hormone (FSH), estradiol (E2) and anti-Müllerian hormone (AMH) levels, antral follicle count (AFC) and ovarian volumes. In addition, the differences in ovarian reserve impairment between endometrioma cystectomy and non-endometrioma cystectomy were investigated. METHODS: In this prospective study, 22 patients of reproductive age (range, 18.35 years) with benign ovarian masses were enrolled to undergo laparoscopic cystectomy. Of whom 12 had endometriomas and 10 had non-endometriomas. On early follicular phase (day 3) of the cycle preceding the operation and three months after the laparoscopic cystectomy, serum levels of FSH, E2 and AMH, AFC and ovarian volumes were measured in all patients. Data were analyzed with Mann-Whitney U-test and Wilcoxon rank test using SPSS ver. 12.0 for statistic analysis. RESULTS: Median level of serum AMH was significantly decreased from 5.48 ng/mL (interquartile range [IQR], 2.80-7.47) before cystectomy to 2.56 ng/mL (IQR, 1.74-4.32) 3 months postoperation (P<0.05). On the other hand, no significant differences in FSH, E2, AFC and ovarian volumes were found between the preoperative and three months postoperative levels. In a subgroup analysis of the pathologic type of the ovarian cyst, postoperative serum AMH levels were significantly decreased in the endometrioma group, but not in the non-endometrioma group. CONCLUSION: Serum AMH levels were significantly decreased after laparoscopic cystectomy without any changes of other ovarian reserve tests.

KR-POK interacts with p53 and represses its ability to activate transcription of p21WAF1/CDKN1A.

Transcriptional regulation by p53 is thought to play a role in its ability to suppress tumorigenesis. However, there remain gaps in understanding about how p53 regulates transcription and how disrupting this function may promote cancer. Here we report a role in these processes for the kidney cancer-related gene KR-POK (ZBTB7C), a POZ domain and Krüppel-like zinc finger transcription factor that we found to physically interact with p53. Murine embryonic fibroblasts isolated from genetically deficient mice (Kr-pok(-/-) MEFs) exhibited a proliferative defect relative to wild-type mouse embryonic fibroblasts (MEF). The zinc finger domain of Kr-pok interacted directly with the DNA binding and oligomerization domains of p53. This interaction was essential for Kr-pok to bind the distal promoter region of the CDKN1A gene, an important p53 target gene encoding the cell-cycle regulator p21WAF1, and to inhibit p53-mediated transcriptional activation of CDKN1A. Kr-pok also interacted with the transcriptional corepressors NCoR and BCoR, acting to repress histone H3 and H4 deacetylation at the proximal promoter region of the CDKN1A gene. Importantly, Kr-pok(-/-) MEFs displayed an enhancement in CDKN1A transactivation by p53 during the DNA damage response, without any parallel changes in transcription of either the p53 or Kr-pok genes themselves. Furthermore, Kr-pok promoted cell proliferation in vitro and in vivo, and its expression was increased in more than 50% of the malignant human kidney cancer cases analyzed. Together, our findings define KR-POK as a transcriptional repressor with a pro-oncogenic role that relies upon binding to p53 and inhibition of its transactivation function.

HPV integration begins in the tonsillar crypt and leads to the alteration of p16, EGFR and c-myc during tumor formation.

The prevalence of human papillomavirus (HPV) infection is high in the oropharyngeal mucosal regions, of which the tonsil is the most commonly affected. There may be a link between HPV and the pathogenesis of tonsillar cancer (TC), because of common anatomical characteristics between cervical and tonsillar cancer. We aimed to clarify whether HPV directly affects the oncogenesis and biologic behavior of TC by making a comparison between infection prevalence, physical status and viral loading numbers, and clinicopathologic prognostic factors. To compare HPV-related molecules between TC and tonsillitis (CFT), p16, survivin, HIF-1alpha, skp-1, cyclin A, cyclin B1, c-myc and EGFR were investigated. We observed a significant difference in HPV prevalence between 52 TCs and 69 CFTs (73.1% vs. 11.6%), and most of the HPVs were type 16 (87.2%) and nonepisomal (94.1%). Most TCs associated with HPV arose from the tonsillar crypts, and tended to be inverted and poorly differentiated. Compared with HPV-negative TC, HPV-positive TC showed a strong association with p16 overexpression (p<0.0001), and an inverse association with EGFR amplification (p=0.0478). HPV-16 integration status was strongly associated with c-myc amplification (p=0.034) and HIF-1alpha overexpression (p=0.022). HPV-16 integration could be directly related to tonsillar carcinogenesis initially in tonsillar crypts, followed by cell cycle aberration such as p16 overexpression related to the G1-S phase.

Evaluation of Denka-Seiken turbidimetric high-sensitivity C-reactive protein assay.

C-reactive protein measured with a high sensitivity method (hsCRP) is an important prognostic indicator in patients with an acute coronary syndrome. We evaluated hsCRP measurement with regard to its precision, functional sensitivity, linearity, and interferences using Denka-Seiken CRP II Latex X2 turbidimetric method on two chemistry autoanalyzers: Olympus AU 640 and Hitachi 747. The coefficients of variation (CV) for within-run and between-run precision of hsCRP were satisfactory on both autoanalyzers. Functional sensitivities, expressed as concentrations associated with 10% total interassay CV, were 0.19 mg/l for the Hitachi 747 analyzer and 0.41 mg/l for the Olympus AU 640. The assay was linear up to 300 mg/l with a wide measuring range, which suggested the possibility of using this hsCRP measurement as an inflammation marker and as a risk marker for coronary heart disease (CHD). No significant interference was observed up to a triglyceride concentration of 34 mmol/l, and up to hemoglobin concentration of 4 g/l. The determination of hsCRP by turbidimetric method was satisfactory and acceptable for CHD risk assessment, as well as for use as a marker of inflammation.