Nitrogen dioxide air pollution near ambient levels is an atherogenic risk primarily in obese subjects: a brief communication

Ambient exposure to nitrogen dioxide, a critical air pollutant in developed countries, is positively associated with cardiovascular mortality and morbidity. Although its cardiovascular effects are predominantly shown in patients with high risk of atherogenesis, no studies have elucidated whether daily exposure to nitrogen dioxide air pollution enhances atherogenic metabolisms, primarily in obese subjects who are susceptible to atherogenesis and subsequent cardiovascular diseases. We used male Otsuka Long-Evans Tokushima Fatty (OLETF) rats as obese subjects and Long-Evans Tokushima (LETO) rats as nonobese controls. The animals were continuously exposed to nitrogen dioxide at a concentration of 0, 0.16, 0.8, or 4.0 ppm from 8 weeks of age through 32 weeks. At 40 weeks of age, levels of body weight, triglyceride, and total cholesterol were significantly greater in the OLETF rats than in the LETO rats. A ratio of high-density lipoprotein (HDL) to total cholesterol was significantly smaller in the former than in the latter. In the LETO rats, nitrogen dioxide exposure significantly decreased only the levels of HDL as compared with clean air exposure. In the OLETF rats, however, nitrogen dioxide exposure at a concentration of 0.16 ppm significantly elevated triglyceride concentration and decreased the ratio of HDL to total cholesterol as well as the levels of HDL. Nitrogen dioxide air pollution near ambient levels is an atherogenic risk primarily in obese subjects.     

Dose-dependent and time-limited proliferation of cultured murine interstitial cells of Cajal in response to stem cell factor

Interstitial cells of Cajal (ICCs) play a role as pacemakers for gastrointestinal movement. Although some in vivo experiments showed that the c-kit receptor tyrosine kinase (KIT) and its ligand, stem cell factor (SCF), might be required for the development of murine ICCs near birth, in vitro experiments would be useful to clarify the role of SCF-KIT system for the development of ICCs. We attempted to establish a culture system in order to investigate the proliferation of ICCs. Murine gastrointestinal cells from embryos or neonates were cultured with SCF and stained with anti-KIT antibody and/or alcian-blue. The numbers of KIT+ cells a n d alcian-blue+ cells we re counted, and the number of KIT+.alcian-blue- cells, which represent ICCs was calculated. Clusters containing KIT+ cells were formed in culture. The number of KIT+.alcian-blue- cells from day-18 post coitum embryos increased in response to SCF up to a concentration of 50 ng/ml or for 8 days. The number of cells from day-2 post-partum neonates increased for 4 days, and then remained constant in the presence of SCF. In contrast, the number of cells from day-6 post-partum neonates did not increase and remained constant, even in the presence of SCF. ICCs showed a dose-dependent and time-limited proliferation in response to SCF in the in vitro culture system used here in.     

Cloning and characterization of a cDNA that encodes a 70-kDa novel human thyroid autoantigen

cDNA clones were isolated by screening a human thyroid carcinoma lambda gt11 library with immunoglobulins purified from serum of a patient with autoimmune Graves' disease. One clone (ML8) containing a 1.25-kilobase (kb) insert hybridized with a single 2.0-kb poly(A+) mRNA in human thyroid and lymphocytes but not in human brain, liver, kidney, or muscle. In addition, this probe also hybridized with a single 2.0-kb poly(A+) mRNA from a rat thyroid cell line (FRTL-5). An apparently full length 2,074-base pair (bp) human cDNA was obtained and sequenced. The nucleotide sequence of the 2,074-bp cDNA includes a 5'-noncoding sequence of 17 bp, a 1827-bp open reading frame, and a 222-bp 3'-noncoding sequence. The canonical polyadenylation signal AATAAA is present 18 bp upstream of the poly(A) tail. This cDNA encodes a 69,812-dalton protein with two potential N-linked glycosylation sites and at least one potential membrane spanning domain. Immunoprecipitation of the in vitro translated protein by sera from several patients with Graves' disease argues that the 69,812-dalton protein is an autoantigen.     

Endothelin-1 stimulates c-fos mRNA expression and acts as a modulator on cell proliferation of rat FRTL5 thyroid cells.

In FRTL5 thyroid cells, endothelin (ET)-1 alone had no effect on DNA synthesis but caused a transient increase in c-fos mRNA levels and stimulated IGF-I induced DNA synthesis and cell proliferation. By contrast, ET-1 inhibited the stimulatory effects of TSH actions on DNA synthesis, cell proliferation and c-AMP production. 8-Bromo-cAMP-induced DNA synthesis was also inhibited by ET-1, suggesting that ET-1 exerts its inhibitory effects at step(s) involving cAMP production and post cAMP pathway. ET-1-induced suppression of TSH actions were reversed by a C-kinase inhibitor, H-7. These results suggest that the effect of ET on functions of FRTL5 cells is, at least, in part mediated by C-kinase dependent pathway.     

Roles of the DNA binding proteins H-NS and StpA in homologous recombination and repair of bleomycin-induced damage in Escherichia coli

The DNA binding protein H-NS promotes homologous recombination in Escherichia coli, but the role of its paralog StpA in this process remains unclear. Here we show that an hns mutant, but not an stpA mutant, are marginally defective in conjugational recombination and is sensitive to the double-strand-break-inducing agent bleomycin. Interestingly, the hns stpA double mutant is severely defective in homologous recombination and more bleomycin-sensitive than is the hns or stpA single mutant, indicating that the stpA mutation synergistically enhances the defects of homologous recombination and the increased bleomycin-sensitivity in the hns mutant. In addition, the transduction analysis in the hns stpA double mutant indicated that the stpA mutation also enhances the defect of recombination in the hns mutant. These results suggest that H-NS plays an important role in both homologous recombination and repair of bleomycin-induced damage, while StpA can substitute the H-NS function. The recombination analysis of hns single, stpA single, and hns stpA double mutants in the recBC sbcA and recBC sbcBC backgrounds suggested that the reduction of the hns single or hns stpA double mutants may not be due to the defect in a particular recombination pathway, but may be due to the defect in a common process of the pathways. The model for the functions of H-NS and StpA in homologous recombination and double-strand break repair is discussed.     

Molecular cloning, heterologous expression, and characterization of a novel member of CYP2A in the Syrian hamster.

The cDNA clone coding for a novel cytochrome P-450 2A subfamily member (CYP2A16) was isolated from a Syrian hamster liver cDNA library. The deduced amino acid sequence of CYP2A16 showed more than 90% identity with those of rat CYP2A3 and mouse CYP2A4/5. The catalytic activity of CYP2A16 was determined by transient expression of its cDNA in transfected COS7 cells and CYP2A16 was found to have the testosterone 2 beta-, 15 alpha-, and 15 beta-hydroxylases, coumarin 7-hydroxylase, and ethoxycoumarin O-deethylase activities. These enzymatic characteristics of CYP2A16 are different from those of other Syrian hamster CYP2A subfamily members, CYP2A8 and CYP2A9. Northern blot analysis showed that CYP2A16 was expressed in kidney and lung while most of the other CYP2A subfamily members have been reported to be expressed in liver and olfactory. These observations indicated that the Syrian hamster CYP2A16 had unique properties compared with those of other CYP2A subfamily members.     

Expression and function of myc during asexual reproduction of the budding ascidian Polyandrocarpa misakiensis

The budding ascidian Polyandrocarpa misakiensis proliferates asexually by budding. The atrial epithelium is a multipotent but differentiated tissue, which transdifferentiates into various tissues and organs after the bud separates from the parental body. We isolated cDNA clones homologous to the myc proto-oncogene from P. misakiensis. The cDNA, named Pm-myc, encoded a polypeptide of 639 amino acid residues, containing Myc-specific functional motifs, Myc box I and Myc box II, and the basic helix-loop-helix domain. Expression of Pm-myc was observed in the atrial epithelium in the organ-forming region of the developing bud, where the epithelial cells dedifferentiate and re-enter the cell cycle. The expression was also observed in fibroblast-like cells, which are known to participate in the organogenesis together with the epithelial cells. Unexpectedly, the atrial epithelium expressed Pm-myc more than one day before the dedifferentiation. The organogenesis was disturbed by Pm-myc-specific double-stranded RNA. In situ hybridization revealed that Pm-myc-positive fibroblast-like cells disappeared around the organ primordium of the dsRNA-treated bud. The results suggest that the mesenchymal-epithelial transition of fibroblast-like cells is important for the organogenesis in this budding ascidian species.     

Comparative studies of irinotecan-loaded polyethylene glycol-modified liposomes prepared using different PEG-modification methods

Recently, a polyethylene glycol (PEG)-modification method for liposomes prepared using pH-gradient method has been proposed. The differences in the pharmacokinetics and the impact on the antitumor effect were examined; however the impact of PEG-lipid molar weight has not been investigated yet. The main purpose of this study is to evaluate the impact of PEG-lipid molar weight against the differences in the pharmacokinetics, the drug-release profile, and the antitumor effect between the proposed PEG-modification method, called the post-modification method, and the conventional PEG-modification method, called the pre-modification method. Various comparative studies were performed using irinotecan as a general model drug. The results showed that PEG-lipid degradation could be markedly inhibited in the post-modification method. Furthermore, prolonged circulation time was observed in the post-modification method. The sustained drug-release was observed in the post-modification method by the results of the drug-releasing test in plasma. Moreover, a higher antitumor effect was observed in the post-modification method. It was also confirmed that the same behaviors were observed in all comparative studies even though the PEG molecular weight was lower. In conclusion, the post-modification method has the potential to be a valuable PEG-modification method that can achieve higher preservation stability of PEG-lipid, prolonged circulation time, and higher antitumor effect with only half the amount of PEG-lipid as compared to the pre-modification method. Furthermore, it was demonstrated that PEG(5000)-lipid would be more desirable than PEG(2000)-lipid since it requires much smaller amount of PEG-lipid to demonstrate the same performances.