Reflood experiments in rod bundles with flow blockages due to clad ballooning

Clad ballooning and the resulting partial flow blockage are one of the major thermal-hydraulic concerns associated with the coolability of partially blocked cores during a loss-of-coolant accident (LOCA). Several in-pile tests have shown that fuel relocation causes a local power accumulation and a high thermal coupling between the clad and fuel debris in the ballooned regions. However, previous experiments in the 1980s did not take into account the fuel relocation phenomena and resulting local power increase in the ballooned regions. The present paper presents the results of systematic investigations on the coolability of rod bundles with flow blockages. The experiments were mainly performed in 5 × 5 rod bundles, 2 × 2 rod bundles and other test facilities. The experiments include a reflood heat transfer, single-phase convective heat transfer, flow redistributions phenomena, and droplet break-up behavior. The effects of the fuel relocation and resulting local power increase were investigated using a 5 × 5 rod bundle. The fuel relocation phenomena increase the peak cladding temperature.

Dual-source, dual-energy multidetector CT for the evaluation of pancreatic tumours

OBJECTIVE

To investigate the potential diagnostic value of dual-energy CT (DECT) with virtual non-enhanced (VNE) and iodine-only images, and to determine the optimal mixed ratio of blended images for evaluation of pancreatic diseases.

METHODS

Multiphasic DECT was performed in 44 patients with focal pancreatic disease. DECT was used during the pancreatic and hepatic venous phases, and a peak kilovoltage of 120 kVp was used for both non-contrast phases. For qualitative analysis of the CT images, two radiologists assessed three image sets (VNE, iodine-only and blended images) in order to determine the acceptability of VNE in replacing true non-enhanced (TNE) images, the added value of iodine-only images and the preferred blending ratio. For quantitative analyses, the CT numbers and image noise of the pancreatic parenchyma, lesions, aorta and psoas muscle were measured. The contrast-to-noise ratio of the lesion was calculated on the pancreatic phase images. The effective radiation dose for DECT and TNE images was calculated. Statistical comparisons were made using the Friedman test, the Wilcoxon test, the paired t-test and repeated measures of analysis of variation with Bonferroni correction for multiple comparisons.

RESULTS

The level of acceptance of the VNE images in replacing TNE images was 90.9%. Regarding the iodine-only images, 50% of the cases were found to have an added value. The linear-blended images with a weighting factor of 0.5 were preferred.

CONCLUSIONS

DECT was able to provide high-quality VNE images that could replace TNE images and iodine-only images showing an added value. Blended images with a weighting factor of 0.5 were preferred by the reviewers.

Erythropoietin enhancer stimulates production of a recombinant protein by Chinese hamster ovary (CHO) cells under hypoxic condition

Oxygen is a limiting nutrient in animal cell culture and its supply is still worthy of improvement for production of useful proteins with a high efficiency. From a different point of view, development of the system by which a high productivity can be maintained even under hypoxic condition as well as under normoxic condition may be important. A number of hypoxia-inducible genes have been found in eucaryotic cells and the induction in most cases, if not all, is due to hypoxic activation of the gene transcription. Transcription of erythropoietin gene is highly hypoxia-inducible and the induction is achieved by binding of a protein, which is widely distributed in animal cells, to a short DNA stretch (erythropoietin enhancer) in the 3' flanking region of erythropoietin gene. Using a hepatoma cell line (Hep3B) that produces the endogenous erythropoietin in an oxygen-dependent manner and Chinese hamster ovary cells that have been widely used for production of recombinant proteins, we show that, under hypoxic condition, the erythropoietin enhancer can activate not only the promoter of erythropoietin gene but also promoters of cytomegalovirus early genes and eucaryotic polypeptide chain elongation factor gene, both of which are very active in animal cells under normoxic condition.

Effects of uwhangchungsimwon on cell viability, proliferation, and gene expression of human neuronal cell line IMR32

Uwhangchungsimwon (pill, UC) is one of the traditional Korean medical prescriptions that has been most frequently used for stroke. To characterize the effects of UC on human neuronal cells, the human neuroblastoma cell line IMR32 was treated with UC, and cell viability, cell proliferation, apoptosis, and gene expression were analyzed. The effect of UC on recovery of cell viability was analyzed following stress induction by nutrient depletion or cold shock. Flow cytometric analysis of the cell cycle showed that UC inhibits cell cycle progression of IMR32 in a dose- and time-dependent manner. UC was also identified to increase cell viability and suppress apoptosis induction by a DNA-damaging agent, etoposide. Quantitative RT-PCR analysis revealed that expressions of the p53 tumor suppressor gene and its downstream effect, Waf1, are stimulated whereas expressions of positive cell cycle regulators, c-Myc, c-Fos, and Cyclin D1 were repressed by UC treatment. Moreover, while expression levels of apoptosis inhibitors, Bcl-2 and Bcl-XL were increased following UC treatment, that of an apoptosis promoter, Bax, was decreased. In addition, expression of BMP-7, which has been recently demonstrated to improve the motor neuron recovery from stroke, was induced by UC while it was not detected in untreated cells. Taken together, our data suggest that the pharmacoclinical effects of UC might be derived in part from its negative regulation of cell proliferation and apoptosis through the transcriptional control of related genes.

Aging, oxidative responses, and proliferative capacity in cultured mouse aortic smooth muscle cells

The cellular mechanisms that contribute to the acceleration of atherosclerosis in aging populations are poorly understood, although it is hypothesized that changes in the proliferative capacity of vascular smooth muscle cells is contributory. We addressed the relationship among aging, generation of reactive oxygen species (ROS), and proliferation in primary culture smooth muscle cells (SMC) derived from the aortas of young (4 mo old) and aged (16 mo old) mice to understand the phenotypic modulation of these cells as aging occurs. SMC from aged mice had decreased proliferative capacity in response to α-thrombin stimulation, yet generated higher levels of ROS and had constitutively increased mitogen-activated protein kinase activity, in comparison with cells from younger mice. These effects may be explained by dysregulation of cell cycle-associated proteins such as cyclin D1 and p27Kip1 in SMC from aged mice. Increased ROS generation was associated with decreased endogenous antioxidant activity, increased lipid peroxidation, and mitochondrial DNA damage. Accrual of oxidant-induced damage and decreased proliferative capacity in SMC may explain, in part, the age-associated transition to plaque instability in humans with atherosclerosis.

The angiopoietin-tie2 system in coronary artery endothelium prevents oxidized low-density lipoprotein-induced apoptosis

OBJECTIVES

A healthy, intact coronary artery endothelium is important because most common coronary artery diseases result from loss of endothelial integrity. In this study, we explored the biological significance of the angiopoietin-Tie2 system in porcine coronary artery.

METHODS

Cultured porcine coronary artery endothelial cells and explanted coronary arteries were used.

RESULTS

Immunohistochemical analyses indicated that Ang1 is selectively expressed in vascular muscular cells, whereas angiopoietin-2 (Ang2) and Tie2 are selectively expressed in endothelial cells. Accordingly, Ang1 mRNA is mainly expressed in cultured porcine coronary artery vascular smooth muscle cells, whereas Ang2 and Tie2 mRNAs are mainly expressed in cultured porcine coronary artery endothelial cells (PCAECs). Ang1 (200 ng/ml) induced Tie2 phosphorylation, while Ang2 (200 ng/ml) did not produce Tie2 phosphorylation. Ang1 increased the survival of cultured PCAECs during apoptosis induced by oxidized low-density lipoprotein (OxLDL). This survival effect was does-dependent and PI. Furthermore, Ang1 also protected endothelial cells of explanted coronary artery against OxLDL-induced apoptosis artery.

CONCLUSION

These results suggest that adult coronary artery contains Ang1-Tie2 components that enhance endothelial cell survival to help maintain the normal integrity of the coronary artery endothelium.

Cell biology of tubotympanum in relation to pathogenesis of otitis media - a review

The sterility of the eustachian tube and tympanic cavity of normal individuals is maintained not only by the adaptive immune system, but also by the mucociliary system and the antimicrobial molecules of innate immunity. Mucin production and periciliary fluid homeostasis are essential for normal mucociliary function and dysfunction of this system is an important risk factor for otitis media. The secreted antimicrobial molecules of the tubotympanum include lysozyme, lactoferrin, beta defensins, and the surfactant proteins A and D (SP-A, SP-D). Defects in the expression or regulation of these molecules may also be the major risk factor for otitis media.

Mucin gene expression in cultured human middle ear epithelial cells

For the advanced study of the cell and molecular biology of middle ear mucosa, an in vitro cell culture system is required. Although middle ear epithelial cells have been cultured from various species of laboratory animal, there have been no reports concerning a serial subculture system of human middle ear epithelial cells. In this paper, we describe the establishment of a primary culture system of human middle ear epithelial cells using a serum-free conditioned medium and the characterization of these cells by the expression of phenotypic characteristics of epithelial cells and mucin genes. Cultured cells were anchorage-dependent in terms of growth and showed a polygonal cobblestone-like appearance: desmosomes in the cell junction were observed by electron microscopy. In the immunocytochemical study, cytokeratin (epithelial cell marker) was expressed in all cultured cells. but von Willebrand factor (endothelial cell marker) was not. Unexpectedly, vimentin (fibroblast marker) was locally expressed, and a double stain showed the co-expression of both cytokeratin and vimentin in the same cell. The products of reverse transcriptase polymerase chain reaction from cultured cells yielded distinct bands compatible with the expected sizes of the MUC1, MUC2, MUC5AC and MUC5B genes. This culture system will allow us to prepare the cell line and to perform advanced studies of human middle ear mucosal biology.

Incidence of presbycusis of Korean populations in Seoul, Kyunggi and Kangwon provinces

Presbycusis, a bilateral sensorineural hearing loss caused by changes in the inner ear, is related to multiple factors such as noise exposure and otologic disease. In institute-based studies, we tried to determine the incidence of presbycusis in Korean populations living in Seoul, Kyunggi and Kangwon provinces by gender and age groups. The subjects were people who had visited health promotion centers. Pure tone audiometry was done over 20 years on 6,028 subjects. In a community-based study, the subjects were elderly residents of Kanghwa-do area. There were no obvious factors that could cause hearing impairment in the subjects. For the pure tone audiometry, hearing threshold was obtained by using the six-dimension method. The incidence of presbycusis for subjects aged 65 years and older was 37.8% and 8.3% for > or = 27 dB HL criterion and > or = 41 dB HL criterion, respectively. The incidence increased with age. A statistically significant difference in the hearing threshold was found between men and women aged 65 years or older. No differences were found between the community-based study and the institute- based studies. There was a high incidence (about 40%) of presbycusis among Koreans aged 65 years or older (for > or = 27 dB HL criterion). With an aging population, we anticipate that this report could be used to provide a basic data for the study of presbycusis.

Effects of retinoic acid, triiodothyronine and hydrocortisone on mucin and lysozyme expression in cultured human middle ear epithelial cells

Mucous hypersecretion is a major complication of otitis media and can prolong the disease course and increase morbidity. Mucin, a major component of mucus, is a macromolecular complex of glycoprotein and makes mucus viscous. Lysozyme is a secretory element of the middle ear mucosa. which has a non-specific and innate antibacterial function. We attempted to identify factors that regulate these secretory products and their morphological phenotype using cultured human middle ear epithelial cells. Cellular differentiation was induced by creating an air liquid interface on culture day 9 in serum-free conditioned media. Omission of retinoic acid (RA) caused decrease in the secretion of mucin and lysozyme, and in the cellular expression of MUC 2, MUC 5AC and MUC 5B mRNA. In contrast, removal of triiodothyronine (T3) caused an increase in the secretion of mucin and the level of MUC5AC mRNA. When hydrocortisone (HC) was removed from the media, the secretion of mucin was decreased with out an apparent change of message level. The expression of MUC 1 mRNA was not changed by the respective deficiency of RA. T3 or HC. The effect of T3 or HC on lysozyme was not significant. This study shows that RA, T3 and HC influence the morphological phenotype and the secretory function of mucin and lysozyme in cultured human middle ear epithelial cells. This culture system can serve as an in vitro model for study of the regulation of various cellular secretions in human middle ear epithelium.

Inhibition of human smooth muscle cell proliferation by gamigeonsim-tang through the transcriptional regulation of cell cycle-controlling genes

The effects of gamigeonsim-tang (GGT) on cellular proliferation and expression of cell cycle-related genes were investigated in human smooth muscle cell HISM. HISM cells were treated with an aqueous extract of GGT. Cellular proliferation was investigated by an immunocytometric analysis of PCNA expression and a flow cytometric analysis of the cell cycle progression. Reduced expression of PCNA and a significant accumulation of G1 phase cells were observed following treatment, indicating that GGT inhibits cellular proliferation of human smooth muscle cells. To explore whether GGT affects the transcription of cell cycle-regulating genes, we evaluated mRNA expression of p53, p21Waf1 PCNA, Cyclin D1, Cdc2, Histone H3, c-Myc, and c-Fos using a quantitative RT-PCR analysis. While increased expressions of two negative cell cycle regulators, p53 and p21Waf1 were found, reduced expressions of cell cycle stimulators, PCNA, c-Fos, and c-Myc, were identified following treatment. Taken together, our study demonstrates that GGT inhibits cellular proliferation of human smooth muscle cell through the up- and down-regulation of growth-inhibiting and growth-promoting genes, respectively.

Activation of caspase cascades in Korean mistletoe (Viscum album var. coloratum) lectin-II-induced apoptosis of human myeloleukemic U937 cells

Mistletoe lectins are of high biological activity and exert cytotoxic effects. We have previously shown that Korean mistletoe, Viscum album var. coloratum, lectin-II specifically induces apoptotic cell death in cancer cells, not normal lymphocytes. The destructive mechanism by mistletoe lectins on tumor cells was mediated by activation of c-JUN N-terminal kinase (JNK)/stress-activated protein kinase. Herein, we investigated the involvement of caspase cascade and its proteolytic cleavage effects on biosubstrates of human myeloleukemic U937 cells by D-galactoside and N-acetyl-galactosamine-specific Korean mistletoe lectin-II. Mistletoe lectin-II induced ladder pattern DNA fragmentation and activation of caspase-3, -8, and -9 of U937 cells, but not caspase-1 protease, in a time- and dose-dependent manner. Consistent with catalytic activation of protease, both poly(ADP-ribose) polymerase (PARP) and protein kinase C-delta (PKC-delta) are also cleaved in mistletoe lectin-II-treated U937 cells. An inhibitor of caspase-3-like protease, DEVD-CHO peptide, significantly inhibited mistletoe lectin-II-induced apoptosis, PARP cleavage, and fragmentation of DNA. These results provide the evidence that Korean mistletoe lectin-II induces apoptotic death of U937 cells via activation of caspase cascades.

Hwansodan protects PC12 cells against serum-deprivation-induced apoptosis via a mechanism involving Ras and mitogen-activated protein (MAP) kinase pathway

Hwansodan has been used as a prescription for senile and vascular dementia in Oriental medicine. We investigated the neuroprotective effects of Hwansodan water extract on the apoptotic death of PC12 cells by serum deprivation. Hwansodan significantly rescued PC12 cells from apoptotic death by serum deprivation in a dose-dependent manner. The nuclear staining of PC12 cells clearly showed that Hwansodan attenuated nuclear condensation and fragmentation, which represents typical neuronal apoptotic characteristics. Hwansodan also prevents DNA fragmentation and caspase-3-like protease activation in serum-deprived PC12 cells and induces the tyrosine phosphorylation of proteins around 44 kDa, which was identified as ERK1 with electrophoretic gel mobility shift by Western blot. In addition, MEK inhibitor PD98059 and Ras inactivator, alpha-hydroxyfarnesylphosphonic acid and mevastatin, attenuated the neuroprotective effects of Hwansodan in serum-deprived PC12 cells. These results indicate that Ras/MEK/ERK signaling pathway plays a role in neuroprotective effects of Hwansodan in serum-deprived PC12 cells.

A new biological strategy for high productivity of recombinant proteins in animal cells by the use of hypoxia-response enhancer

Oxygen supply is one of the major problems in the production of useful proteins by cultured animal cells and therefore it is of importance to devise a system by which a high productivity of human therapeutic recombinant proteins can be maintained or enhanced under low oxygen concentrations. A number of hypoxia-inducible genes have been found in animal cells and the induction in most cases is due to hypoxic activation of the gene transcription. A consensus sequence (HRE = hypoxia-response enhancer) responsible for the hypoxic activation exists in these genes and the binding of a protein, which is widely distributed in animal cells, to this sequence responding to hypoxia activates the promoter activity. The promoter of lactate dehydrogenase A gene is active in Chinese hamster ovary (CHO) cells and the vicinal HRE stimulates the promoter activity efficiently in hypoxia. We have prepared a number of permanent CHO cell lines producing recombinant human erythropoietin (Epo) under control of this promoter/HRE. Epo production was highly hypoxia-inducible when the wild-type of HRE was used but uninducible when the mutant HRE was used. There was little difference in the in vitro and in vivo activities, and glycosylation between Epo produced by the cells cultured in 21% and 2% oxygen. Furthermore, forced expression of hypoxia-inducible factor-1alpha (HIF-1alpha) enhanced Epo production in all oxygen concentrations. These results indicate that a biological strategy based on the hypoxic induction of gene transcription provides a novel system which guarantees a high productivity even uner low oxygen concentrations.

Design and synthesis of highly potent fumagillin analogues from homology modeling for a human MetAP-2

New fumagillin analogues were designed through structure-based molecular modeling with a human methionine aminopeptidase-2. Among the fumagillin analogues, cinnamic acid ester derivative CKD-731 showed 1000-fold more potent proliferation inhibitory activity on endothelial cell than TNP-470.

A case of Sweet's syndrome in patient with dermatomyositis

Sweet's syndrome (SS) has been reported as an association with malignant neoplasms and autoimmune diseases, e.g., Behçet's disease, Sjogren's syndrome, and rheumatoid arthritis. But dermatomyositis (DM), one of the rare autoimmune diseases, was not reported as an associated disease of SS. We describe an interesting case of SS associated with DM. Diagnosis was made by skin biopsy, and subsequent clinical resolution occurred after institution of prednisolone.

Secretory production of erythropoietin and the extracellular domain of the erythropoietin receptor by Bacillus brevis: affinity purification and characterization

Bacillus brevis secretes a large amount of cell wall proteins into the culture medium. For construction of Bacillus brevis expression-secretion vectors of human erythropoietin (EPO) and the extracellular domain of mouse erythropoietin receptor (sEPOR), cDNA for each mature form was inserted into a plasmid containing the promoter region and the signal-peptide encoding region of a cell wall protein. Culture supernatants of transformants were affinity purified using a monoclonal antibody-fixed gel for EPO and and EPO-fixed gel for sEPOR. The affinity purification efficiently removed unwanted proteins, giving samples with sufficiently high purity to analyze amino acid sequences of N-terminal regions and biological activities. Combination of this secretory production and affinity purification may facilitate isolation of a large amount of pure EPO and sEPOR, and is useful for further understanding the molecular mechanism of interaction between EPO and EPOR.

Comparison of speech recognition ability with different speech processing strategies by Korean cochlear implantees

Many variables affect the audiologic performance of cochlear implantees. With current methods of evaluation, it is difficult to directly compare auditory function with different speech coding strategies. We compared the audiologic performance directly with F0F1F2 and multipeak speech coding strategies in the same implanted ear of eight Korean cochlear implantees. We tested word and phoneme recognition abilities using Korean word lists for speech audiometry and two-syllable nonsense words, respectively. With the multipeak coding strategy, a significant difference in discrimination ability was found in the initial fricative consonant phonemes (/s/,/ss/,/h/). Our results suggest that the improvement of speech recognition ability with the multipeak coding strategy comes primarily from the better understanding of the initial fricative consonants.