Induced in vitro differentiation of neural-like cells from human exfoliated deciduous teeth-derived stem cells

Stem cells from human exfoliated deciduous teeth (SHED) are highly proliferative, clonogenic and multipotent stem cells with a neural crest cell origin. Additionally, they can be collected with minimal invasiveness in comparison with other sources of mesenchymal stem cells (MSCs). Therefore, SHED could be a desirable option for potential therapeutic applications. In this study, SHEDs were established from enzyme-disaggregated deciduous dental pulp obtained from 6 to 9 year-old children. The cells had typical fibroblastoid morphology and expressed antigens characteristic of MSCs, STRO1, CD146, CD45, CD90, CD106 and CD166, but not the hematopoietic and endothelial markers, CD34 and CD31, as assessed by FACS analysis. Differentiation assessment revealed a strong osteogenic and adipogenic potential of SHEDs. In order to further evaluate the in vitro differentiation potential of SHED into neural cells, a simple short time growth factor-mediated induction was used. Immunofluorescence staining and flow cytometric analysis revealed that SHED rapidly expressed nestin and b-III tubulin, and later expressed intermediate neural markers. In addition, the intensity and percentages of nestin and b-III tubulin and mature neural markers (PSA-NCAM, NeuN, Tau, TH, or GFAP) increased significantly following treatment. Moreover, RT-PCR and Western blot analyses showed that the neural markers were strongly up-regulated after induction. In conclusion, these results provide evidence that SHED can differentiate into neural cells by the expression of a comprehensive set of genes and proteins that define neural-like cells in vitro. SHED cells might be considered as new candidates for the autologous transplantation of a wide variety of neurological diseases and neurotraumatic injuries.     

Two new end-to-end single dicyanamide bridged Cu(II) complexes with Schiff base ligands: Structural, electrochemical and magnetic properties

The synthesis, crystal structures and magnetic properties of two different copper(II) complexes of formula [Cu(L¹)(dca)]_n · nClO₄ (1) and [Cu(L²)]₂(dca)(ClO₄) (2) [L¹ = N,N-dimethylethylene-N′-(pyridine-2-carbaldiiminato), HL² = N,N-dimethylethylene-N′-salicylaldiiminato, dca = dicyanamide anion] are described. Spectroscopic and electrochemical properties have also been discussed. A one-dimensional chain structure with single, symmetrical, μ_1,5-dca bridges is found in compound 1. The copper atom in 1 has a square pyramidal geometry. A tridentate Schiff base ligand, having NNN donor sites, and one nitrogen atom from dca occupy the basal plane. N(18) of a neighbouring unit occupies the apical site. The Schiff base used in compound 2 is a tridentate anion with NNO donor sites, which changes the structure in a dinuclear unit of copper atoms bridged by single end-to-end dicyanamide ion. The environment around copper in 2 is square planar. Magnetic susceptibility measurements for 1 and 2 reveal the occurrence of weak antiferromagnetic interaction through the dca ligand.     

Respiratory effects of N-methyl-D-aspartate on the ventrolateral medullary surface

We studied the central effects of N-methyl-D-aspartate (NMDA) on respiration in 18 artificially ventilated cats anesthetized with alpha-chloralose. Unilateral topical application of NMDA (1 x 10(-8) mol) to the intermediate region of the ventrolateral medulla exaggerates the phrenic response to CO2 at end-tidal PCO2 levels of less than 50.0 Torr. At higher end-tidal PCO2 levels, however, such differences disappear. Unilateral NMDA application increases the activity of the right and left phrenic nerves equally. Furthermore, the magnitude of the phrenic response after unilateral application of NMDA was not different from that after bilateral application. NMDA also had a vasopressor action when applied to the ventrolateral medullary surface. In contrast to respiratory responses, bilateral application of NMDA caused a significant increase in blood pressure compared with unilateral application of NMDA. Application of the NMDA antagonist 2-amino-5-phosphonovaleric acid abolished both the blood pressure and respiratory effects of NMDA. These results suggest that CO2 and NMDA may act on a common respiratory premotoneuron to produce stimulation of breathing. Because blood pressure responses, unlike respiratory responses, were greater after bilateral application than after unilateral application of NMDA, it is suggested that the neural substrates for the two effects of NMDA seem to be different.     

The Interaction between Polynucleotide Kinase Phosphatase and the DNA Repair Protein XRCC1 Is Critical for Repair of DNA Alkylation Damage and Stable Association at DNA Damage Sites

XRCC1 plays a key role in the repair of DNA base damage and single-strand breaks. Although it has no known enzymatic activity, XRCC1 interacts with multiple DNA repair proteins and is a subunit of distinct DNA repair protein complexes. Here we used the yeast two-hybrid genetic assay to identify mutant versions of XRCC1 that are selectively defective in interacting with a single protein partner. One XRCC1 mutant, A482T, that was defective in binding to polynucleotide kinase phosphatase (PNKP) not only retained the ability to interact with partner proteins that bind to different regions of XRCC1 but also with aprataxin and aprataxin-like factor whose binding sites overlap with that of PNKP. Disruption of the interaction between PNKP and XRCC1 did not impact their initial recruitment to localized DNA damage sites but dramatically reduced their retention there. Furthermore, the interaction between PNKP and the DNA ligase IIIα-XRCC1 complex significantly increased the efficiency of reconstituted repair reactions and was required for complementation of the DNA damage sensitivity to DNA alkylation agents of xrcc1 mutant cells. Together our results reveal novel roles for the interaction between PNKP and XRCC1 in the retention of XRCC1 at DNA damage sites and in DNA alkylation damage repair.     

Preparation and characterization of a soluble dextran alpha(1) proteinase inhibitor complex

Purified human alpha(1) proteinase inhibitor, a plasma glycoprotein with a molecular weight of 5.3 x 10(4) daltons and a major serine protease inhibitor has been covalently coupled to dextrans with molecular weights of 1.77 x 10(4) and 1.03 x 10(4) daltons. The coupled conjugates were soluble in aqueous medium and stable up to 6 months at +5 degrees C. Increased moles of dextran/mole protein ratio during coupling resulted in progressive decreases of inhibitory capacity, immunogenicity, and the association constant (k(assoc)) between the enzyme and the inhibitor. Compared to the native protein, the soluble conjugates showed improved stability at pH 3.0 and heat stability at 60 degrees C. At 60 degrees C, no loss of inhibitory capacity has been seen up to 60 min for the conjugates during which time the native protein lost greater than 90% of its inhibitory capacity. The presence of antioxidant catalase was needed to prevent oxidative degradation by hydrogen peroxide.     

Bedraggled, a putative transporter, influences the tissue polarity complex during the R3/R4 fate decision in the Drosophila eye

The tissue polarity pathway is required for the establishment of epithelial polarity in a variety of vertebrate and invertebrate organs. Core tissue polarity proteins act in a dynamically regulated complex to direct the polarization of the Drosophila eye. We report the identification and characterization of bedraggled (bdg), a novel gene that regulates one output of the tissue polarity pathway--the establishment of the R3/R4 photoreceptor fates. bdg encodes a novel, putative transporter protein and interacts genetically with all of the core polarity genes to influence the specification of the R3 and R4 cell fates. Finally, bdg is required for both viability and the initial stages of imaginal disc development.     

Bioenergetic considerations in the improvement of oil content and quality in oil-seed crops

Summary Production values (PVs), defined as the weight of the end product/weight of the substrate required for carbon skeletons and energy production, were calculated for plant fatty acids. The PVs varied from 0.361 to 0.300 with linolenic acid having the lowest value. In general, the PVs of unsaturated fatty acids were lower than those of saturated fatty acids of similar chain lengths. Using this basic information, PVs of (A) oils from different oilseed crops, based on their standard fatty acid composition and (B) seed biomass with specified oil content and fatty acid composition were calculated. 1/PV gives the glucose required for the biosynthesis of 1 g end product and thus an estimate of the photosynthate requirement for the desired breeding goal can be estimated. Such calculations show that increasing oil percentage in seeds has a maximum energy cost when the increase in oil is associated with a decrease in the amount of carbohydrates where there is no change in protein concentration. Reduction of erucic acid content in the rapeseed oil did not alter its PV. It is inferred that there are no serious bioenergetic constraints in altering the fatty acid composition.     

Biomimetic synthesis and anti-HIV activity of dimeric phloroglucinols

Plants are an important source of a variety of bioactive compounds with different modes of action. Anti-HIV agents from plant sources can be useful in developing novel therapies for inhibiting HIV infection. Based on the reported anti-HIV activity of plant derived phloroglucinols, several new dimeric phloroglucinols were synthesized in the present study by varying substitution on aromatic ring and at methylene bridge. Some of the synthesized compounds have shown good HIV inhibitory activity in a human CD4+ T cell line (CEM-GFP) infected with HIV-1 NL_4.3 virus isolate. Structure–activity studies indicate that phenyl, 4-benzyloxy-1-phenyl and cyclohexyl substitution at methylene bridge gave compounds with better anti-HIV activity. Compounds 22 and 24 showed highest anti-HIV activity with an IC₅₀ of 0.28 μM and 2.71 μM, respectively, former was more active than the positive standard AZT in cell based assay.