Ultraviolet A Regulates Adipogenic Differentiation of Human Adipose Tissue-derived Mesenchymal Stem Cells via Up-regulation of Kruppel-like Factor 2

Adipocyte dysfunction is strongly associated with the development of obesity, which is a major risk factor for many disorders, including diabetes, hypertension, and heart disease. This study shows that ultraviolet A (UVA) inhibits adipogenic differentiation of human adipose tissue-derived mesenchymal stem cells and its action mechanisms. The mRNA levels of peroxidase proliferator-activated receptor (PPAR) γ and CCAAT/enhancer-binding protein α (C/EBPα), but not CCAAT/enhancer-binding protein ((C/EBP) β and δ, were reduced by UVA. Moreover, the mRNA levels of PPAR γ target genes (lipoprotein lipase (LPL), CD36, adipocyte protein (aP2), and liver X receptor α (LXR)) were down-regulated by UVA. Additionally, attempts to elucidate a possible mechanism underlying the UVA-mediated effects revealed that UVA induced migration inhibitory factor (MIF) gene expression, and this was mediated through activation of AP-1 (especially JNK and p42/44 MAPK) and nuclear factor-κB. In addition, reduced adipogenesis by UVA was recovered upon the treatment with anti-MIF antibodies. AMP-activated protein kinase phosphorylation and up-regulation of Kruppel-like factor 2 (KLF2) were induced by UVA. Taken together, these findings suggest that the inhibition of adipogenic differentiation of human adipose tissue-derived mesenchymal stem cells by UVA occurs primarily through the reduced expression of PPAR γ, which is mediated by up-regulation of KLF2 via the activation of MIF-AMP-activated protein kinase signaling.     

Reemerging vivax malaria: changing patterns of annual incidence and control programs in the Republic of Korea

Changing patterns of the reemerging Plasmodium vivax malaria in the Republic of Korea (South Korea) during the period 1993 to 2005 are briefly analyzed with emphasis on the control measures used and the effects of meteorological and entomological factors. Data were obtained from the Communicable Diseases Monthly Reports published by the Korea Center for Disease Control and Prevention, and webpages of World Health Organization and United Nations. Meteorological data of Kangwon-do (Province) were obtained from local weather stations. After its first reemergence in 1993, the prevalence of malaria increased exponentially, peaking in 2000, and then decreased. In total, 21,419 cases were reported between 1993 and 2005 in South Korea. In North Korea, a total of 916,225 cases were reported between 1999 and 2004. The occurrence of malaria in high risk areas of South Korea was significantly (P > 0.05) correlated with the mosquito population but not with temperature and rainfall. Control programs, including early case detection and treatment, mass chemoprophylaxis of soldiers, and international financial aids to North Korea for malaria control have been instituted. The situation of the reemerging vivax malaria in the Republic of Korea is remarkably improving during the recent years, at least in part, due to the control activities undertaken in South and North Korea.     

Electrochemical properties of heme-protein in lauric acid films and its application as a biosensor

In this research, the enhancement of electron-transfer activity of hemoglobin (Hb) in lauric acid film was investigated for the first time. This type of composite film was made on a glassy carbon electrode by a casting method. Cyclic voltammetric result of the modified electrode displays a well-defined redox peak, which was attributed to the direct electrochemical response of Hb. Our results illustrate that Hb exchange electrons directly with electrode and exhibits the characteristics of peroxidase. When we use this modified electrode as a biosensor, it gives excellent performance in the electrocatalytic reduction of hydrogen peroxide (H₂O₂). The parameters such as pH and applied potential of the biosensor influencing in H₂O₂ detection were optimized carefully. Through the optimal conditions, the proposed biosensor shows the linear range for H₂O₂ determination was from 1×10⁻⁵ to 1.25×10⁻⁴ mol L⁻¹ with a detection limit of 1×10⁻⁷ mol L⁻¹. The biosensor retained more than 90% of the initial response after 14 d.     

Mechanism of the pH-Induced Conformational Change in the Sensor Domain of the DraK Histidine Kinase via the E83, E105, and E107 Residues

The DraR/DraK two-component system was found to be involved in the differential regulation of antibiotic biosynthesis in a medium-dependent manner; however, its function and signaling and sensing mechanisms remain unclear. Here, we describe the solution structure of the extracellular sensor domain of DraK and suggest a mechanism for the pH-dependent conformational change of the protein. The structure contains a mixed alpha-beta fold, adopting a fold similar to the ubiquitous sensor domain of histidine kinase. A biophysical study demonstrates that the E83, E105, and E107 residues have abnormally high pKa values and that they drive the pH-dependent conformational change for the extracellular sensor domain of DraK. We found that a triple mutant (E83L/E105L/E107A) is pH independent and mimics the low pH structure. An in vivo study showed that DraK is essential for the recovery of the pH of Streptomyces coelicolor growth medium after acid shock. Our findings suggest that the DraR/DraK two-component system plays an important role in the pH regulation of S. coelicolor growth medium. This study provides a foundation for the regulation and the production of secondary metabolites in Streptomyces.     

A microsatellite polymorphism in intron 2 of human Toll-like receptor 2 gene: functional implications and racial differences

The human Toll-like receptor 2 (TLR2) mediates responses of both innate and adaptive immunity to Gram-positive bacteria, including mycobacteria. We sought functional polymorphisms in the 5'-untranslated region (UTR) of TLR2. We found a highly polymorphic (GT)n dinucleotide repeat 100 bp upstream of the TLR2 translational start site in intron 2. The numbers of GT repeats varied from 12 to 28. There were significant differences in allele distribution between African Americans and Caucasians (P=0.008) and between African Americans and Koreans (P=0.0003). The promoter activities of recombinant promoter-intron2/reporter constructs including the shortest [GT)n=12] or longest [(GT)n=28] alleles were significantly more stimulated when exposed to 200 IU ml(-1) of interferon-gamma than when exposed to 100 IU ml(-1) of GM-CSF (P<==0.03). Since TLR2 plays a critical role in the human innate immune response, this functional microsatellite polymorphism may be important in the pathogenesis of infectious and inflammatory diseases.     

Biosynthesis of plant-specific phenylpropanoids by construction of an artificial biosynthetic pathway in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Biological synthesis of plant secondary metabolites has attracted increasing attention due to their proven or assumed beneficial properties and health-promoting effects. Phenylpropanoids are the precursors to a range of important plant metabolites such as the secondary metabolites belonging to the flavonoid/stilbenoid class of compounds. In this study, engineered Escherichia coli containing artificial phenylpropanoid biosynthetic pathways utilizing tyrosine as the initial precursor were established for production of plant-specific metabolites such as ferulic acid, naringenin, and resveratrol. The construction of the artificial pathway utilized tyrosine ammonia lyase and 4-coumarate 3-hydroxylase from Saccharothrix espanaensis, cinnamate/4-coumarate:coenzyme A ligase from Streptomyces coelicolor, caffeic acid O-methyltransferase and chalcone synthase from Arabidopsis thaliana, and stilbene synthase from Arachis hypogaea.     

Ornithodoros sawaii (Ixodida: Argasidae) Larvae Collected from Hydrobates monorhis on Sogugul and Gaerin Islands,Jeollanam-do (Province), Republic of Korea

The 65th Medical Brigade and Public Health Command District-Korea, in collaboration with the Migratory Bird Research Center, National Park Research Institute, conducted migratory bird tick surveillance at Sogugul and Gaerin Islands (small rocky bird nesting sites), Jeollanam-do (Province), Republic of Korea (ROK), on 30 July and 1 August 2009. Breeding seabirds captured by hands in their nesting burrows were banded, identified to species, and carefully examined for ticks during the nesting season. A total of 9 Ornithodoros sawaii larvae were removed from 4 adult Hydrobates monorhis (Swinhoe’s storm petrel). The identification of the larvae of O. sawaii collected from migratory seabirds were molecularly confirmed using mitochondrial 16S rDNA primer sets.     

Brassinolide interacts with auxin and ethylene in the root gravitropic response of maize (Zea mays)

This study examines how brassinolide (BL) and ethylene interact in the gravitropic response mechanism of maize ( Zea mays ) primary roots. When applied exogenously, ethylene increases the rate of gravitropic curvature in a dose-dependent manner. This effect of ethylene was confirmed by the fact that AVG, a specific action inhibitor of ACC synthase, reduces the gravitropic curvature in the presence and absence of BL. Since AVG did not inhibit BL-increased gravitropic curvature completely, we investigated the possibility that BL may act on the gravitropic response by ways other than simply through enhanced ethylene production. We show that BL exhibits some of its stimulatory effect in the absence of ethylene. In addition, BL reduces the presentation time and lag period for the gravitropic response, whereas ethylene increases them. One possible mechanism of such action is that BL affects protein kinase activity, since the protein kinase inhibitors, staurosporine and H89, reduce BL-increased gravitropic curvature. In summary, BL is involved in the gravitropic response in maize primary roots via ethylene production, but it acts in a way that differs somewhat from that of ethylene.