Calcium transport in dispersed acinar cells from rat pancreas

The present studies were performed to attempt to elucidate the basis for the discrepancy between results of Kondo and Schulz (1976, Biochim. Biophys Acta 419, 76–92), who found that cholecystokinin and cholinergic agents increase uptake of ⁴⁵Ca by dispersed acinar cells from rat pancreas, and results of others (Matthews, E.K., Petersen, O.H. and Williams, J.A. (1973) J. Physiol. 234, 689–701; Chandler, D.E. and Williams, J.A. (1974) J. Physiol. 243, 831–846; Case, R.M. and Clausen, T. (1973) J. Physiol. 235, 75–102; Gardner, J.D., Conlon, T.P., Klaeveman, H.L., Adams, T.D. and Ondetti, M.A. (1975) J. Clin. Invest. 56, 366–375; Christophe, J.P., Frandsen, E.K., Conlon, T.P., Krishna, G. and Gardner, J.D. (1976) J. Biol. Chem. 251, 4640–4645; Shelby, H.T., Gross, L.P., Lichty, P. and Gardner, J.D. (1976) J. Clin. Invest. 58, 1482–1493 and Deschodt-Lanckman, M., Robberecht, P., de Neef, P., Lammens, M. and Christophe, J. (1976) J. Clin. Invest. 58, 891–898). They have reported that cholecystokinin and cholinergic agents do not alter or cause a slight decrease in uptake of ⁴⁵Ca by pancreatic acinar cells. Our present results indicate that increased uptake of ⁴⁵Ca by acinar cells incubated with cholecystokinin occurs only in cells washed with iced, 160 mM choline chloride and reflects increased cellular uptake of radioactivity from the wash solution but not from the incubation medium. We detected no effect of cholecystokinin on uptake of ⁴⁵Ca by cells washed with 160 mM choline chloride containing 5 mM ethylenediaminetetraacetate or by cells washed with Krebs-Ringer bicarbonate. Furthermore, cells washed with 160 mM choline chloride accumulated a substantial amount of ⁴⁵Ca from the wash solution and this accumulation was increased in cells that had been preincubated with cholecystokinin. Cells washed with Krebs-Ringer bicarbonate did not take up ⁴⁵Ca from the wash solution.     

Gel formation with leucocytes and heparin

Heparin in concentrations of 5–225 units/ml caused suspensions of thymus lymphocytes, spleen or bone marrow cells to gel. The extent of gel formation was related to concentration of heparin and of cells. The reaction was observed only with intact cells and was temperature-dependent. It did not require Ca⁺⁺, was not inhibited with EDTA, adenosine, prostaglandin synthetase inhibitors, or phosphodiesterase inhibitors and, in this respect, differed from platelet aggregation induced by heparin. Since heparin is released along with histamine from mast cells during injury and certain forms of allergic reaction, a possible role for heparin in promoting accumulation of white cells in the extravascular space is suggested.     

Inhibition of the mixed lymphocyte culture by peritoneal exudate cells.

Inhibition of mixed lymphocyte cultures (MLC) by macrophages and by supernatants of short term cultured macrophages was assessed by incorporation of ³H-thymidine (TdRH3) and also by blast cell counts and by determination of cellmediated lympholysis. Peritoneal exudate cells (PEC) induced by thioglycollate, at concentrations >10%, inhibited all three parameters of MLC. Lower concentrations of PEC, and supernatants from cultured PEC, inhibited TdRH3 incorporation, but had no significant effect on blast cell counts or on generation of cytotoxic effector cells. Inhibition by the supernatants could be reversed by dialysis or by use of low specific activity TdRH3. These data indicate that macrophages can inhibit proliferative responses in MLC, but that this must be carefully distinguished from selective inhibition of TdRH3 incorporation.     

Acetylcholinesterase triggers the aggregation of PrP 106-126

Acetylcholinesterase (AChE), a senile plaque component, promotes amyloid-beta-protein (Abeta) fibril formation in vitro. The presence of prion protein (PrP) in Alzheimer's disease (AD) senile plaques prompted us to assess if AChE could trigger the PrP peptides aggregation as well. Consequently, the efficacy of AChE on the PrP peptide spanning-residues 106-126 aggregation containing a coumarin fluorescence probe (coumarin-PrP 106-126) was studied. Kinetics of coumarin-PrP 106-126 aggregation showed a significant increase of maximum size of aggregates (MSA), which was dependent on AChE concentration. AChE-PrP 106-126 aggregates showed the tinctorial and optical amyloid properties as determined by polarized light and electronic microscopy analysis. A remarkable inhibition of MSA was obtained with propidium iodide, suggesting that AChE triggers PrP 106-126 and Abeta aggregation through a similar mechanism. Huprines (AChE inhibitors) also significantly decreased MSA induced by AChE as well, unveiling the potential interest for some AChE inhibitors as a novel class of potential anti-prion drugs.     

On the nucleotide binding domain of fructose-1,6-bisphosphatase.

Native chicken liver fructose-1,6-bisphosphatase (Fru-P₂ase) can bind to blue dextranSepharose affinity column and is not displaced by its sugar-phosphate substrate; however; it is readily eluted by the inhibitor 5′-AMP. Treatment of Fru-P₂ase with pyridoxal 5′-phosphate (pyridoxal-P) in the presence of the substrate, fructose 1,6-bisphosphate, followed by reduction with NaBH₄ leads to the formation of active pyridoxal-P derivatives of the enzyme showing diminished sensitivity to AMP inhibitor. The modified enzyme does not bind to the affinity column. On the other hand, in the presence of AMP modification of Fru-P₂ase with pyridoxal-P occurs at the catalytic site; this modification does not alter its binding behavior toward the dye ligand. Blue dextran can also protect Fru-P₂ase against AMP inhibition, and it is a competitive desensitizer for the nucleotide ligand. The results establish that blue dextran binds specifically to the allosteric site of the enzyme, and that the structure of this site may resemble that of the dinucleotide fold in other enzymes. Like native Fru-P₂ase, digestion of pyridoxal-P-Fru-P₂ase (with regulatory properties altered) with subtilisin causes a severalfold increase in the catalytic activity measured at pH 9.2, without significant change in the activity at pH 7.5, and produces a peptide with 56 amino acids. The residual subunit, M_r ~ 30,000, was found to contain all of the incorporated pyridoxal-P.     

Planar tetrameric metal cluster formation at room temperature induced by π?π interactions: 3D supramolecular host containing 1D channel filled with solvent methanol

A novel tetrameric metal cluster, [La₂(phen)₃(2,3-pdc)(NO₃)₄(H₂O)]₂·(CH₃OH)₂ (2,3-pdcH₂ = pyridine-2,3-dicarboxylic acid, phen = 1,10-phenanthroline), have been synthesized at room temperature from water-methanol mixture by mixing the reactants in stoichiometric ratio. 2,3-Pdc and their π?π interactions played a vital role on the construction of the core. The auxiliary ligand, phen, which blocked the outermost periphery of the molecule and their hydrophobic π?π interactions facilitate the formation of the tetrameric metal clusters. The tetrameric metal clusters are connected by supramolecular interactions to form 3D supramolecular metal organic host (MOSH) producing supramolecular channels along a-axis. These supramolecular channels are filled up by solvent methanol molecules. The luminescent investigations reveal that cluster complex exhibits strong blue emission.     

MEK5/ERK5/mef2: A novel signaling pathway affected by hepatitis C virus non-enveloped capsid-like particles

Hepatitis C virus (HCV) is an RNA positive strand virus, member of the Flaviviridae family. The viral particle is composed of a capsid containing the genome, surrounded by E1 and E2 proteins, however different forms of viral particles have been observed including non-enveloped particles. Previous reports have proposed that hepatitis C non-enveloped capsid-like particles (HCVne) enter cells of hepatic origin via clathrin-mediated endocytosis, during which different signaling events occur. In this report we show that HCVne particles are capable of inducing the recently discovered ERK5 pathway, in a dose dependent way. The ERK5 pathway can be activated by growth factors and other extracellular signals. This specific activation occurs through a well characterized upstream kinase, MEK5, and is capable of inducing gene regulation of mef2. In contrast, when HCV core structural and NS5A non-structural proteins were expressed endogenously no activation of this pathway was detected. These cell signaling events could be of critical importance and might give clues for the elucidation of cellular manifestations associated with HCV infection.     

大鼠miR-126慢病毒表达载体的构建及其在肝星状细胞中的表达

目的：肝星状细胞（hepaticstellatecell,HSC）激活并发生表型改变是肝纤维化形成的关键,本实验期待通过构建慢病毒mo—miR．126,并体外转染Hsc,为研究miR．126在肝纤维化中的作用奠定实验基础。方法：PCR扩增miR-126的前体,构建miR．126的重组表达载体pCDH．CMV-MCS．EFl．copGFP-miR．126,脂质体法转染包装细胞293TN细胞,包装产生慢病毒,以293TN细胞绿色荧光蛋白（greenfluorescentprotein,GFP）的表达水平测定病毒滴度,构建重组慢病毒（Lentivims,LV）载体（Lv．miR．126）,体外转染活化的HSC．T6,荧光显微镜观察荧光阳性细胞百分率,real—timePCR检测miR一126转入水平。结果：经PCR扩增检测阳性菌落和测序证实,成功构建携带大鼠miR一126基因重组慢病毒载体。倒置荧光显微镜下观察可见包装细胞293TN呈绿色荧光,并测得滴度108〉ifu／ml。荧光显微镜下HSC的荧光阳性率在95％以上。Real—timePCR检测证实miR-126转染后获得了较高的表达。结论：成功构建大鼠慢病毒载体Lv—miR-126,并可在体外高效稳定表达,为本研究后续对miR-126靶点验证和功能研究奠定实验基础。     

Bioelectronics meets nanomedicine for cardiovascular implants: PEDOT-based nanocoatings for tissue regeneration

Background

An exciting direction in nanomedicine would be to analyze how living cells respond to conducting polymers. Their application for tissue regeneration may advance the performance of drug eluting stents by addressing the delayed stent re-endothelialization and late stent thrombosis.

Methods

The suitability of poly (3, 4-ethylenedioxythiophene) (PEDOT) thin films for stents to promote cell adhesion and proliferation is tested in correlation with doping and physicochemical properties. PEDOT doped either with poly (styrenesulfonate) (PSS) or tosylate anion (TOS) was used for films' fabrication by spin coating and vapor phase polymerization respectively. PEGylation of PEDOT: TOS for reduced immunogenicity and biofunctionalization of PEDOT: PSS with RGD peptides for induced cell proliferation was further applied. Atomic Force Microscopy and Spectroscopic Ellipsometry were implemented for nanotopographical, structural, optical and conductivity measurements in parallel with wettability and protein adsorption studies. Direct and extract testing of cell viability and proliferation of L929 fibroblasts on PEDOT samples by MTT assay in line with SEM studies follow.

Results

All PEDOT thin films are cytocompatible and promote human serum albumin adsorption. PEDOT:TOS films were found superior regarding cell adhesion as compared to controls. Their nanotopography and hydrophilicity are significant factors that influence cytocompatibility. PEGylation of PEDOT:TOS increases their conductivity and hydrophilicity with similar results on cell viability with bare PEDOT:TOS. The biofunctionalized PEDOT:PSS thin films show enhanced cell proliferation.

Conclusions

The application of PEDOT polymers has evolved as a new perspective to advance stents.

General significance

In this work, nanomedicine involving nanotools and novel nanomaterials merges with bioelectronics to stimulate tissue regeneration for cardiovascular implants. This article is part of a Special Issue entitled Organic Bioelectronics — Novel Applications in Biomedicine.