Representation of a protein molecule as a tree and application to modular computer programs which calculate and modify atomic coordinates

The concept and representation of a logical tree as defined in computer science is applied to obtain a suitable representation of protein molecules in computer programs which handle or calculate atomic coordinates of protein molecules. On the basis of this analysis and of the analysis of the calculation and modification of the structure of a protein from bond lengths, bond angles, and dihedral angles, which is reproduced in an appendix, program modules which accomplish the various required computations are described. Three such modules are given in Iverson notation; in fact, it is hoped that this article will serve as a reasonably complete basis for the preparation of machine programs by moderately proficient programmers.     

Biomarkers of the metabolic syndrome: influence of selected foodstuffs,containing bioactive components

The influence of various non-nutritive bioactive foodstuffs and food components on the biomarkers of the metabolic syndrome in humans is critically reviewed. Tea, coffee, cocoa, soy, olive oil, fruit and nuts are most of the time found to be effective in improving lipid profiles, CRP and adiponectin. Spices (garlic, curcumin and cinnamon), carotenoids and the phytosterol/-stanols are frequently related to lower risk of metabolic syndrome and improved biomarkers. Since food is a complex matrix and the heterogeneity of studied population and served diets are not always well-defined, this could explain some contradictory results found in literature. Other factors jeopardizing definite conclusions are mentioned.     

650. CYNORKIS GUTTATA

Cynorkis guttata Hermans & P. J. Cribb in Cynorkis sect. Gibbosorchis , a recently-described orchid from Madagascar, is illustrated. The identities of Cynorkis purpurascens Lindl., C. calanthoides Kraenzlin and the artificial hybrid C . 'Kewensis' are explained.     

Lack of Rapid Desensitization of Ca2+ Responses in Transfected CHO Cells Expressing the Rat Neurotensin Receptor Despite Agonist-Induced Internalization

Abstract: Transfected Chinese hamster ovary cells were used as a model for the study of the desensitization of the neurotensin receptor at the second messenger level. Stimulation with nanomolar concentrations of neurotensin elicited rapid rises in the cytosolic calcium concentration ([Ca²⁺]_i), which remained elevated throughout the peptide application. A significant response was already detected with neurotensin concentrations as low as 0.01 nM. This high efficiency of neurotensin in mediating this calcium response contrasts with the nanomolar affinity of the peptide for its receptor measured in binding experiments. Evidence indicated that the initial elevation of the [Ca²⁺]_i resulted from release of Ca²⁺ from intracellular stores, whereas the sustained response involved an influx of extracellular origin. Return to the basal level was only reached after extensive washing of the peptide or its displacement with the neurotensin receptor antagonist SR48692. After washing, further stimulations were still able to mediate an increase in the [Ca²⁺]_i, indicating an apparent absence of rapid desensitization of the intracellular signaling pathway that mediates calcium mobilization. In contrast with this absence of response desensitization, the neurotensin receptors were found to internalize after stimulation with the peptide. This internalization was maximal after 30 min and accounted for ～70% of the number of neurotensin binding sites located at the cell surface. These results indicate that despite the functional properties of the rat neurotensin receptor present in Chinese hamster ovary cells after transfection, the intracellular signaling pathway triggered by stimulation with neurotensin seems to be resistant to desensitization. This might be related to the high efficiency of the intracellular signaling pathway coupled to the neurotensin receptor observed in these cells. A possible absence of desensitization of the neurotensin receptor itself is also discussed.