Oligomerization Aiming at Phosphonate Analogues of Oligoadenylates

Abstract

This work deals with isopolar, phosphonate-based nucleotide analogues containing a bridging P-C bond instead of the ester P-O linkage. Specifically, starting from activated derivatives 1, 2, and 3, a simple process for preparation of mixtures of short oligomers and their analyses were elaborated.     

Inhibition of cell-substratum attachment of cultured rat heart cells by protein synthesis inhibitors

Addition of cycloheximide to growth medium of neonatal rat heart cell cultures prevented cell-substratum attachment. Even concentrations of cycloheximide which inhibited only 50% of normal protein synthesis prevented some cells from attaching. Cells which required the longest time to attach were most dependent on protein synthesis. The kinetics of cell-substratum adhesion in the presence of various concentrations of cycloheximide supported the hypothesis that repair of damaged cell membranes was required prior to attachment. An alternate hypothesis that protein synthesis was required for substratum attachment either to synthesize new unique proteins or higher concentrations of existing proteins not damaged by enzymes was not supported by experimentally obtained data. If the second hypothesis were true, no cells would have attached when protein synthesis was completely inhibited (greater than 95%) and all cells should have been equally affected by protein synthesis inhibition; such was not the case. Inhibition of mRNA formation by actinomycin D also should have inhibited attachement completely and this was not observed. Since attachment was minimally affected by actinomycin D, protein synthesis on long-lived mRNA was apparently sufficient for cell-substratum adhesion.     

Physical properties of arabinofuranosylcytosine diphosphate diacylglycerol,an antitumor liponucleotide

Dispersed from a dry film into buffer (5 mM phosphate, 0.15 M NaCl, pH 7.4), the liponucleotide 1-β-d-arabinofuranosylcytosine 5′-diphosphate l-1,2-diacylglycerol (ara-CDPdiacylglycerol) spontaneously forms vesicles which are several microns in diameter and probably unilamellar. Their average size immediately begins to decrease, and after 2 h none can be seen in the light microscope. During 1–2 days in unstirred solutions at 25°C, the vesicles are transformed to spherical or nearly spherical micelles having an apparent partial specific volume of 0.835 ml·g^?1, a maximum possible aggregation number of about 150, and an anhydrous radius of about 37 Å. The critical micelle concentration (CMC) is about 10 μM in buffer and 20 μM in distilled water, but micelle-monomer equilibration requires at least 1 week at a total concentration of 66 μM. This exceedingly slow equilibration is unique among reported detergents. The standard enthalpy and entropy of micellization are ?13 kJ·mol^?1 and 87 J·mol^?1·K^?1, respectively. These values are within the range reported for other detergents. Sonication accelerates the vesicle-micelle transformation to 30 min.     

Glycoside modification of oleanolic acid derivatives as a novel class of anti-osteoclast formation agents

Oleanolic acid, a natural product, possesses an anti-osteoclast formation activity. Targeting at discovery of novel and potent anti-bone resorption agents, 22 glycosides of oleanolic acid derivatives (including d-galactopyranosides, d-glucopyranosides, d-xylopyranoses, d-arabopyranoses and d-glycuronic acids) were synthesized at phase-transfer-catalyzed conditions (K₂CO₃, Bu₄NBr, CH₂Cl₂-H₂O) and their inhibitory activity on the formation of osteoclast-like multinucleated cells (OCLs) induced by 1α, 25-dihydroxy vitamin D₃ was evaluated in a co-culture assay system. The structure-activity relationships of these compounds were also discussed.     

Endothelial Cell Tube Formation Assay for the In Vitro Study of Angiogenesis

Angiogenesis is a vital process for normal tissue development and wound healing, but is also associated with a variety of pathological conditions. Using this protocol, angiogenesis may be measured in vitro in a fast, quantifiable manner. Primary or immortalized endothelial cells are mixed with conditioned media and plated on basement membrane matrix. The endothelial cells form capillary like structures in response to angiogenic signals found in conditioned media. The tube formation occurs quickly with endothelial cells beginning to align themselves within 1 hr and lumen-containing tubules beginning to appear within 2 hr. Tubes can be visualized using a phase contrast inverted microscope, or the cells can be treated with calcein AM prior to the assay and tubes visualized through fluorescence or confocal microscopy. The number of branch sites/nodes, loops/meshes, or number or length of tubes formed can be easily quantified as a measure of in vitro angiogenesis. In summary, this assay can be used to identify genes and pathways that are involved in the promotion or inhibition of angiogenesis in a rapid, reproducible, and quantitative manner.     

Development of cranial muscles in the actinopterygian fish Senegal bichir,Polypterus senegalus Cuvier, 1829

Polypterus senegalus Cuvier, 1829 is one of the most basal living actinopterygian fish and a member of the Actinopterygii. We analyzed the spatial and temporal pattern of cranial muscle development of P. senegalus using whole‐mount immunostaining and serial sectioning. We described the detailed structure of the external gill muscles which divided into dorsal and ventral parts after yolk exhaustion. The pattern of the division is similar to that of urodeles. We suggest that, the external gill muscles of P. senegalus are involved in spreading and folding of the external gill stem and the branches. The fibers of the external gill muscles appear postero‐lateral to the auditory capsule. In addition, the facial nerve passes through the external gills. Therefore, the external gill muscles are probably derived from the m. constrictor hyoideus dorsalis. In contrast to previous studies, we described the mm. interhyoideus and hyohyoideus fibers as independent components in the yolk‐sac larvae. The m. hyohyoideus fibers appear lateral to the edge of the ventral portion of the external gill muscles, which are probably derived from the m. constrictor hyoideus dorsalis. These findings suggest that the m. hyohyoidues is derived from the m. constrictor hyoideus dorsalis in P. senegalus . In other actinopterygians, the m. hyohyoideus is derived from the m. constrictor hyoideus ventralis; therefore, the homology of the m. hyohyoidues of P. senegalus and other actinopterygians remains unclear. J. Morphol. 278:450–463, 2017. © 2017 Wiley Periodicals, Inc.