Dexamethasone-induced differentiation of pancreatic AR42J cell involves p21(waf1/cip1) and MAP kinase pathway

Dexamethasone converts pluripotent pancreatic AR42J cells into exocrine cells expressing digestive enzymes. In order to address molecular mechanism of this differentiation, we have investigated the role of mitogen-activated protein (MAP) kinase pathway and gene expressions of p21(waf1/cip1) and nuclear oncogenes (c-fos and c-myc) during AR42J cell differentiation. Dexamethasone markedly increased the intracellular and secreted amylase contents as well as its mRNA level. However, cell growth and DNA content were significantly decreased. With these phenotypic changes, AR42J cells induced transient mRNA expression of p21(waf1/cip1) gene, which reached maximal level by 6 h and then declined gradually toward basal state. In contrast to p21(waf1/cip1), c-fos gene expression was transiently inhibited by 6 h and then recovered to basal level by 24 h. Increased c-myc expression detected after 3 h, peaked by 12 h, and remained elevated during the rest of observation. Dexamethasone inhibited epidermal growth factor-induced phosphorylation of extracellular signal regulated kinase. Inhibition of MAP kinase pathway by PD98059 resulted in further elevation of the dexamethasone-induced amylase mRNA and p21(waf1/cip1) gene expression. These results suggest that p21(waf1/cip1) and nuclear oncogenes are involved in dexamethasone-induced differentiation and inhibition of MAP kinase pathway accelerates the conversion of undifferentiated AR42J cells into amylase-secreting exocrine cells.     

Serum concentrations of soluble 4-1BB and 4-1BB ligand correlated with the disease severity in rheumatoid arthritis

Rheumatoid arthritis (RA) is a multifactorial autoimmune disease whose etiopathogenesis is not well understood. Although soluble (s) forms of 4-1BB (s4-1BB) and 4-1BB legand (s4-1BBL) have been detected in the sera of RA patients, their significance is not known. We compared the serum levels of s4-1BB and s4-1BBL in RA patients with those in systemic lupus erythematosus (SLE) and Behcet's disease (BD) patients. Serum levels of s4-1BB and s4-1BBL were significantly higher in RA patients compared with healthy controls, SLE or BD patients, and the abundance was correlated with disease severity in patients with RA. The serum levels of s4-1BB in RA patients were inversely corroborated with 4-1BB expression levels on activated T lymphocytes. In addition, there was a correlation between serum levels of s4-1BB and s4-1BBL. The augmented secretion of s4-1BB and s4-1BBL levels into the serum may reflect the clinical symptoms of RA and levels of s4-1BB and s4-1BBL in sera at the time of diagnosis may be indicative of the severity and outcome of RA.     

A kinetic study of the oxidation of uranium dioxide

Summary A kinetic model for the oxidation of a UO₂ pellet is suggested by considering the mass transfer and the diffusion of oxygen molecules. The kinetic parameters were estimated by a fitting of the experimental data. The activation energies for the chemical reaction and the product layer diffusion were calculated from the kinetic model. The suggested model explains well the oxidation behavior of UO₂.     

Conformation Analysis of Ile-Ala-Val-Pro Peptide and Its Derivatives by Circular Dichroism

Ile-Ala-Val-Pro as a hypocholesterolemic peptide was isolated from soybean protein. We have synthesized four peptides, Ile-Ala-Val-Pro-Gly-Glu-Val-Ala, Leu-Ile-Ala-Val-Pro-Gly-Glu-Val-Ala, Ile-Ala-Val-Pro-Thr-Gly-Val-Ala, Leu-Ile-Ala-Val-Pro-Thr-Gly-Val-Ala, with a conserved Ile-Ala-Val-Pro amino acid sequence, for circular dichroism investigations. These four peptide sequences were also found in the amino acid sequence in soybean protein, which was defined from the genomic sequence. Additionally for a detailed analysis of conformation features of these peptides, the Ile-Ala-Val-Pro and Leu-Ile-Ala-Val-Pro were also synthesized. All peptides were prepared using standard fluorenylmethyloxycarbonyl methodology and the peptide yields ranged from 90 to 95% of the theoretical yields with purity after purification above 99%.     

An approach to enhance specificity against RNA targets using heteroconjugates of aminoglycosides and chloramphenicol (or linezolid)

We describe the design and synthesis of new heterodimeric conjugates, which are comprised of a neomycin B (Neo) stem-binding component and a chloramphenicol (Cam) or linezolid (Lnz) loop-binding component. Some of the heterodimeric conjugates display enhanced affinities to RNA targets and that binding occurs in both stem and loop regions of the RNA. In addition, the results of foot-printing and mutation studies suggest that the enhanced binding affinity of the conjugates is RNA sequence-specific.     

Analysis of underivatized amino acid mixtures using high performance liquid chromatography/dual oscillating nebulizer atmospheric pressure microwave induced plasma ionization-mass spectrometry

A dual oscillating capillary nebulizer (OCN) in conjunction with an atmospheric pressure microwave induced plasma ionization (AP-MIPI) source was applied to the analysis of underivatized amino acid mixtures. It was found that, compared to the single OCN, the dual OCN enhanced the sensitivity of detection several fold. Enhanced sensitivity was compound dependent. For small molecules, such as amino acids, it was 2-5 times more sensitive, while for larger molecules such as peptides it was more than an order of magnitude. The increase in sensitivity was attributed to the enhanced nebulization of the new torch. By using water/ acetonitrile containing 0.1% nonafluoropentanoic acid as the high performance liquid chromatography (HPLC) mobile phase and a C18 column, all common amino acids were separated and detected. A comparison between the results obtained using microwave induced plasma, atmospheric pressure chemical ionization (APCI), and electrospray ionization (ESI) at flow rates compatible with micro LC (10-100 microL/min) showed a higher sensitivity of detection with the AP-MIPI technique for the analysis of underivatized amino acids.     

Isolation and Identification of Peptides from Soy 11S-Globulin with Hypocholesterolemic Activity

A peptide with hypocholesterolemic activity was isolated by HPLC from the pepsin hydrolysate of 11S-globulin. Its molecular weight (755.2 Da) and amino-acid sequence (Ile-Ala-Val-Pro-Gly-Glu-Val-Ala) were established. The hypocholesterolemic effect was determined by analysis of bile-acid binding and the percent inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase in vitro. The lowering of the cholesterol content is explained by bile acids bound to hydrolysate peptides shielding them from reabsorption and stimulating the transformation of cholesterol in blood plasma. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 585–588, November–December, 2005.     

Quantitative Determination of Octylonium in Human Plasma by LC–MS

The purpose of this investigation was to develop a method for measuring the concentration of octylonium in human plasma. Hydrochloric acid was added to the plasma samples before pretreatment to improve the stability of the octylonium. After liquid–liquid extraction with ethylacetate and isopropanol (10:1), the analytes were separated by chromatography on a reversed-phase C₁₈ column and detected by LC–MS–MS with electrospray ionization–ionization. The coefficient of variation for the precision of the assay was less than 10.1%, and the accuracy ranged from 98.0 to 106.5%. The limit of quantification or sensitivity was 0.2 ng mL⁻¹. This method was validated by measuring octylonium in the plasma of healthy human subjects after administration of a single 120-mg oral dose of octylonium bromide. Thus, a highly sensitive and accurate analytical method was developed to determine the concentration of octylonium in human plasma.