Two previously undescribed cholestanol saponins from the rhizomes of Paris fargesii var. petiolata.

Two previously undescribed cholestanol saponins, parpetiosides F - G (1-2), and six known analogs (3-8) were isolated from the rhizomes of Paris fargesii var. petiolata. Their structures were elucidated by extensive spectroscopic data analysis and chemical methods. Compound 1 was a rare 6/6/6/5/5 fused-rings cholestanol saponin with disaccharide moiety linked at C-26 of aglycone which was hardly seen in genus Paris. All of these compounds were discovered in this plant for the first time. In addition, the cytotoxicities of saponins (1-8) against three human cancer cell lines (U87, HepG2 and SGC-7901) were evaluated by CCK-8 method, and saponins 5-8 displayed certain cytotoxicities. The strong interactions between saponins 5-8 and SCUBE3, an oncogene for glioma cells, were displayed by molecular docking.

A new 3D contour extraction method for tooth cavity in a dental CAD/CAM system.

In dental CAD/CAM system, tooth restoration produces customized tooth with a prepared cavity, while the prosthetic tooth fitting is firstly determined by the contour feature of the cavity, the cavity contour extraction of the tooth is one of the important issue. In order to accurately extract the cavity contour, a new Three-Dimension (3D) optimal path searching algorithm based on Intelligent Scissors theory is presented. In this algorithm, the 3D tooth is firstly formulated as a weighted model, by calculating the minimum weigh sum of the local cost from a start point to an end point in the cavity edge, the initial optimal contour can be acquired. Then through restricting the path searching range and searching direction, a desired contour can be extracted dynamically. The cases study results show that the algorithm produces a 3D mathematically piece-wise optimal contour on the cavity edge, which can be used directly for tooth design. This method simplifies the tooth design processes and increases the design efficiency.

Cloning, expression and mutagenesis of a subunit contact of rabbit muscle-specific (betabeta) enolase.

The cDNA for rabbit muscle-specific (betabeta) enolase was cloned, sequenced and expressed in Escherichia coli. This betabeta-enolase differs at eight positions from that sequenced by Chin (17). Site-directed mutagenesis was used to change residue 414 from glutamate to leucine, thereby abolishing a salt bridge involved in subunit contacts. Recombinant wild-type and mutant enolase were purified from E. coli and compared to enolase isolated from rabbit muscle. Molecular weights were determined by mass spectrometry. All three betabeta-enolases had similar kinetics, and UV and circular dichroism (CD) spectra. The mutant enolase was far more sensitive to inactivation by pressure, by KCl or EDTA, and by sodium perchlorate. We confirmed, by analytical ultracentrifugation, that the sodium perchlorate inactivation was due to dissociation. DeltaG(o) for dissociation of enolase was decreased from 49.7 kJ/mol for the wild-type enzyme to 42.3 kJ/mol for the mutant. In contrast to the wild-type enzyme, perchlorate inactivation of E414L was accompanied by a small loss of secondary structure.