Poly(diiododiacetylene): preparation, isolation, and full characterization of a very simple poly(diacetylene).

Poly(diiodiacetylene), or PIDA, is a conjugated polymer containing the poly(diacetylene) (PDA) backbone but with only iodine atom substituents. The monomer diiodobutadiyne (1) can be aligned in the solid state with bis(nitrile) oxalamide hosts by hydrogen bonds between oxalamide groups and weak Lewis acid-base interactions (halogen bonds) between nitriles and iodoalkynes. The resulting cocrystals start out pale blue but turn shiny and copper-colored as the polymerization progresses.

D4 receptor deficiency in mice has limited effects on impulsivity and novelty seeking.

Alleles of the human dopamine D(4) receptor (D(4)R) gene (DRD4.7) have repeatedly been found to correlate with novelty seeking, substance abuse, pathological gambling, and attention-deficit hyperactivity disorder (ADHD). If these various psychopathologies are a result of attenuated D(4)R-mediated signaling, mice lacking D(4)Rs (D(4)KO) should be more impulsive than wild-type (WT) mice and exhibit more novelty seeking.

Universal cell labelling with anionic magnetic nanoparticles.

Magnetic labelling of living cells creates opportunities for numerous biomedical applications, from individual cell manipulation to MRI tracking. Here we describe a non-specific labelling method based on anionic magnetic nanoparticles (AMNPs). These particles first adsorb electrostatically to the outer membrane before being internalized within endosomes.

Trastuzumab therapy vs tetracycline controlled ERBB2 downregulation: influence on tumour development in an ERBB2-dependent mouse tumour model.

Trastuzumab (Herceptin) has improved therapy of breast cancer. Only patients overexpressing ERBB2 are treated with trastuzumab, whereas its use in tumours without ERBB2 expression is useless. This led to the concept that the subgroup of trastuzumab-sensitive tumours is 'ERBB2-dependent', meaning that ERBB2 signalling is indispensable for growth of these tumours.

[Molecular tumour therapy: antibodies and small molecules].

Molecular tumor therapy based on understanding the principles of malignant transformation has resulted in a dramatic progress in cancer therapy. Targeted therapies attack the malignant cells and, more specifically, the deregulated intracellular signal transduction. Therefore a high efficacy with lower side effects then classical chemotherapy is expected.

Pressure-induced polymerization of diiodobutadiyne in assembled cocrystals.

Diiodobutadiyne forms cocrystals with bis(pyridyl)oxalamides in which the diyne alignment is near the ideal parameters for topochemical polymerization to the ordered conjugated polymer, poly(diiododiacetylene) (PIDA). Nonetheless, previous efforts to induce polymerization in these samples via heat or irradiation were unsuccessful. We report here the successful ordered polymerization of diiodobutadiyne in these cocrystals, by subjecting them to high external pressure (0.

The importance of grana stacking for xanthophyll cycle-dependent NPQ in the thylakoid membranes of higher plants.

In the present study we have examined the effects of grana stacking on the rate of violaxanthin (Vx) de-epoxidation and the extent of non-photochemical quenching of chlorophyll a fluorescence (NPQ) in isolated thylakoid membranes of spinach. Our results show that partial and complete unstacking of thylakoids in reaction media devoid of sorbitol and MgCl(2) did not significantly affect the efficiency of Vx de-epoxidation. Under high light (HL) illumination we found slightly higher values of Vx conversion in stacked membranes, whereas in thylakoids incubated at pH 5.

Different microtubule motors move early and late endocytic compartments.

Important progress has been made during the past decade in the identification of molecular motors required in the distribution of early and late endosomes and the proper trafficking along the endocytic pathway. There is little direct evidence, however, that these motors drive movement of the endosomes. To evaluate the contributions of kinesin-1, dynein and kinesin-2 to the movement of early and late endosomes along microtubules, we made use of a cytosol-free motility assay using magnetically isolated early and late endosomes as well as biochemical analyses and live-cell imaging.

Lobeline effects on tonic and methamphetamine-induced dopamine release.

The mechanisms of interaction between lobeline and the dopamine transporter (DAT) or the vesicular monoamine transporter (VMAT-2) are not clear. The goal of this study was to elucidate the effects of lobeline on these transporters in a cell system co-expressing the DAT and VMAT-2. Lobeline caused release of [(3)H]dopamine to a similar extent as reserpine (VMAT-2 inhibitor), but was less efficacious than methamphetamine or dopamine.

The influence of phase transitions in phosphatidylethanolamine models on the activity of violaxanthin de-epoxidase.

In the present study, the influence of the phospholipid phase state on the activity of the xanthophyll cycle enzyme violaxanthin de-epoxidase (VDE) was analyzed using different phosphatidylethanolamine species as model lipids. By using (31)P NMR spectroscopy, differential scanning calorimetry and temperature dependent enzyme assays, VDE activity could directly be related to the lipid structures the protein is associated with. Our results show that the gel (L beta) to liquid-crystalline (L alpha) phase transition in these single lipid component systems strongly enhances both the solubilization of the xanthophyll cycle pigment violaxanthin in the membrane and the activity of the VDE.

Molecular analysis of the CHD7 gene in CHARGE syndrome: identification of 22 novel mutations and evidence for a low contribution of large CHD7 deletions.

Purpose: Autosomal dominant CHARGE syndrome (OMIM no. 214800) is characterized by choanal atresia or cleft lip or palate, ocular colobomas, cardiovascular malformations, retardation of growth, ear anomalies, and deafness, and is caused by mutations in the CHD7 gene. Here, we describe the outcome of a molecular genetic analysis in 18 Finnish and 56 German patients referred for molecular confirmation of the clinical diagnosis of suspected CHARGE syndrome.

In vivo imaging of transplanted hepatocytes with a 1.5-T clinical MRI system--initial experience in mice.

The feasibility of in vitro mature mouse hepatocyte labeling with a novel iron oxide particle was assessed and the ability of 1.5-T magnetic resonance imaging (MRI) to track labeled mouse hepatocytes in syngenic recipient livers following intraportal cell transplantation was tested. Mouse hepatocytes were incubated with anionic iron oxide nanoparticles at various iron concentrations.

Structurally flexible macro-organization of the pigment-protein complexes of the diatom Phaeodactylum tricornutum.

By means of circular dichroism (CD) spectroscopy, we have characterized the organization of the photosynthetic complexes of the diatom Phaeodactylum tricornutum at different levels of structural complexity: in intact cells, isolated thylakoid membranes and purified fucoxanthin chlorophyll protein (FCP) complexes. We found that the CD spectrum of whole cells was dominated by a large band at (+)698 nm, accompanied by a long tail from differential scattering, features typical for psi-type (polymerization or salt-induced) CD. The CD spectrum additionally contained intense (-)679 nm, (+)445 nm and (-)470 nm bands, which were also present in isolated thylakoid membranes and FCPs.

Mouse lines selected for alcohol consumption differ on certain measures of impulsivity.

Background: Alcoholics and heavy drinkers score higher on measures of impulsivity than nonalcoholics and light drinkers. This may be due to factors that predate drug exposure (e.g.

Tumour cell toxicity of intracellular hyperthermia mediated by magnetic nanoparticles.

Intracellular hyperthermia is a process by which malignant cells can be selectively killed by heat generated by nanomediators located inside the cell. Here we show that maghemite anionic nanoparticles are efficiently captured by human prostatic tumor cells (PC3) and concentrate within intracellular vesicles. When submitted to an alternative magnetic field, maghemite nanocrystals generate heat from the cell inside, inducing a temperature elevation of eight degree in a loose pellet of 20 million magnetically labeled cells.

The lipid composition of the unicellular green alga Chlamydomonas reinhardtii and the diatom Cyclotella meneghiniana investigated by MALDI-TOF MS and TLC.

The lipid composition of algae is crucial for numerous structural and physiological aspects, e.g. the integrity of the photosynthetic complexes and the functionality of membrane-embedded processes as the photosynthetic electron transport in thylakoids or the mitochondrial respiration.

Spectroscopic and molecular characterization of the oligomeric antenna of the diatom Phaeodactylum tricornutum.

The photosynthetic antenna system of diatoms contains fucoxanthin chlorophyll a/c binding proteins (FCPs), which are membrane intrinsic proteins showing high homology to the light harvesting complexes (LHC) of higher plants. In the present study, we used a mild solubilization of P. tricornutum thylakoid membranes in combination with sucrose density gradient centrifugation or gelfiltration and obtained an oligomeric FCP complex (FCPo).

Intracellular heating of living cells through Néel relaxation of magnetic nanoparticles.

Maghemite and cobalt ferrite anionic magnetic nanoparticles enter tumor cells and can be used as heat sources when exposed to a high-frequency magnetic field. Comparative studies of the two particles enable to unravel the magnetic heating mechanisms (Néel relaxation vs. Brown relaxation) responsible for the cellular temperature rise, and also to establish a simple model, adjusted to the experimental results, allowing to predict the intracellular heating efficiency of iron oxide nanoparticles.

The in vitro kinetics of the interactions between PEG-ylated magnetic-fluid-loaded liposomes and macrophages.

Binding and uptake kinetics of magnetic-fluid-loaded liposomes (MFL) by endocytotic cells were investigated in vitro on the model cell-line J774. MFL consisted of unilamellar phosphatidylcholine vesicles (mean hydrodynamic diameter close to 200nm) encapsulating 8-nm nanocrystals of maghemite (gamma-Fe(2)O(3)) and sterically stabilized by introducing 5mol% of distearylphosphatidylcholine poly(ethylene glycol)(2,000) (DSPE-PEG(2,000)) in the vesicle bilayer. The association processes with living macrophages were followed at two levels.

Synchroma grande spec. nov. (Synchromophyceae class. nov., Heterokontophyta): an amoeboid marine alga with unique plastid complexes.

Chromist algae including the Heterokontophyta are supposed to have evolved monophyletically by secondary endosymbiosis from a eukaryotic host cell that engulfed a eukaryotic red alga. The red algal endosymbiont was then reduced to a secondary plastid surrounded by four enveloping membranes. On the basis of the amoeboid marine alga Synchroma grande gen.

Magnetic targeting of nanometric magnetic fluid loaded liposomes to specific brain intravascular areas: a dynamic imaging study in mice.

Purpose: To prospectively determine, by using dynamic imaging, whether a magnet placed over a specific area of the mouse brain could target systemically administered rhodamine-labeled magnetic fluid-loaded liposomes (MFLs) to that brain region.

Materials And Methods: Experiments were performed with a French Ministry of Agriculture permit and regional ethics committee authorization. In seven anesthetized C57BL/6 mice, a closed cranial window was implanted above the left parieto-occipital cortex.

Magnetic control of vascular network formation with magnetically labeled endothelial progenitor cells.

We describe the applications of new cellular magnetic labeling method to endothelial progenitor cells (EPC), which have therapeutic potential for revascularization. Via their negative surface charges, anionic magnetic nanoparticles adsorb non-specifically to the EPC plasma membrane, thereby triggering efficient spontaneous endocytosis. The label is non-toxic and does not affect the cells' proliferative capacity.

Magnetic control of Dictyostelium aggregation.

We report the control of cell migration by external magnetic forces during the early stage of Dictysostelium discoideum morphogenesis. Magnetically labeled aggregating cells respond to the presence of a magnetic field created by a thin magnetic tip: forces as low as 30 pN are sufficient to elicit the aggregation of the cells at the extremity of the tip. This induced magnetotaxis is competitive to classical chemotaxis.