Live single-cell molecular analysis by video-mass spectrometry.

The direct molecular analysis of a live single cell viewed under a video-microscope has been developed. The cell contents are sucked into a nano-electrospray tip, and hundreds of peaks of ionic compounds of low molecular weight are detected by nano-ESI Q-TOF mass spectrometry (MS). Cell-specific MS peaks in a single mouse-embryonic fibroblasts cell are extracted by a t-test, and one of the peaks is proceeded to MS/MS analysis for molecular identification. This method is direct and quick to identify the molecules of a cell with simultaneous observation by a video-microscope.     

Circular dichroism of tail-to-tail bisbenzyliso-quinoline and the absolute configuration of daurisoline isolated from Menispermum dauricum

Since two asymmetric centres are usually present in the bisbenzylisoquinolines, the circular dichroism is known to be an important method to elucidate their stereochemistry. We studied the relationships of the CD spectra with the stereochemistry of synthetic RR-(1), SS-(2), RS-daurisoline (3) and SR-daurisoline (4). By comparision of the CD spectrum of natural daurisoline (1) from Menispermum dauricum (Menispermaceae) with those of synthetic enantiomers, the absolute configuration was established as RR-daurisoline (1).     

Structure-activity correlation of flavonoids for inhibition of bovine lens aldose reductase

To clarify the structure-activity correlation of flavonoids for inhibition of aldose reductase, about fifty flavonoid compounds were screened. The presence of hydrophobic substituents on the A ring and hydrophilic substituents on the B ring of the flavonoid skeleton was suggested to improve the potency of inhibitory activity. The activities of extracts of Scutellaria baicalensis, Andrographis paniculata and Gutierrezia microcephala are also described.     

Constructive generation of very hard 3-colorability instances

Graph colorability (COL), is a typical constraint satisfaction problem to which phase transition phenomena (PTs), are important in the computational complexity of combinatorial search algorithms. PTs are significant and subtle because, in the PT region, extraordinarily hard problem instances are found, which may require exponential-order computational time to solve. To clarify PT mechanism, many studies have been undertaken to produce very hard instances, many of which were based on generate-and-test approaches. We propose a rather systematic or constructive algorithm that repeats the embedding of 4-critical graphs to arbitrarily generate large extraordinarily hard 3-colorability instances. We demonstrated experimentally that the computational cost to solve our generated instances is of an exponential order of the number of vertices by using a few actual coloring algorithms and constraint satisfaction algorithms.