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Separation and quantitative determination of imipramine and desipramine from rat biological samples by high pressure liquid chromatography
No full textImipramine and its metabolite, desipramine, have been determined in several rat biological samples by high pressure liquid chromatography. The method allows one to detect 15 ng in column of both drugs with a lower sensitivity limit of 20 μg l-1. © 1978 Birkhäuser Verlag
Quantitative structure activity relationships in 1-substituted ureidophenoxy-3-amino-2-propanols, a class of beta adrenergic blocking agents
No full textThe β-adrenergic blocking potency of 56 1-substituted ureidophenoxy-3-amino-2-propanols has been analysed in terms of the linear Free-Wilson model. The values obtained for the Free-Wilson coefficients have been correlated with the chemico-physical parameters of the substituents. The preliminary indication given by the Free-Wilson analysis has been confirmed by a quantitative regression analysis, carried out in the frame of the 'mixed approach' method
Carotenoid and ultrastructure variations during amyloplast to chromoplast trasformation in the ripening fruit of Arum italicum Miller.
No full textCarotenoid and ultrastructure variations in plastids of Arum italicum miller fruit during maturation and ripening
No full textThe changes in the pigment pattern and composition occurring in the Arum italicum berry during the various steps of maturation (ivory to deep-green stages) and ripening (yellow and red-orange stages) were studied and correlated to the ultrastructural modifications of plastids. Transmission electron microscopy showed that each stage was characterized by a specific plastidial type following the unusual sequence amyloplastchloroplastchromoplast. Plastidial transitions were accompanied by profound modifications in the pigmental composition, in particular, in the pattern of carotenoids and their precursors. The HPLC analysis of the carotenoids showed that, besides the two usual all-trans metabolic pathways leading to lutein through alfa-carotene and to auroxanthin through ß-carotene, an additional cis-isomeric biosynthetic pathway leading to cis-neoxanthin through cis-ß-carotene exists. During the pre-ripening stages, the three pathways were present even if with qualitative and quantitative variations. When complete ripening was reached, a block occurred at the cyclization level causing the accumulation of both all-trans (i.e. gamma-carotene and neurosporene) and cis-isomer (i.e. lycopene and zeta-carotene) carotene precursors. Because of the occurrence of unusual pigments and the presence of the three main plastidial types, the fruit of A. italicum may constitute a most instructive model for the study of carotenogenesis
Protoanemonin-induced cytotoxic effects in Euglena Gracilis
No full textThe changes that protoanemonin, an antimicrobial agent of natural origin, brought about in the alga Euglena gracilis were studied with light and electron microscopy and with flow cytometry. The compound proved lethal for the alga at a dose of 5 x 10-5 M. At the sublethal dose of 3.5 x 10-5 M it caused: marked inhibition of growth; increase in the average cell volume; inhibition of cytokinesis and induction of coenocytic organisms; loss of the flagellum and stigma. Most nuclei were arrested in the G2/M phase of the cellular cycle. The chloroplasts were still well organized, but there was a conspicuous decrease in carotenoids and chlorophylls a and b, with a corresponding increase in pheophytins. The multifarious alterations seen in Euglena are discussed on the basis of a possible interaction between this lactone and several enzymatic systems
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Intra-tissue characteristics of chloroplasts in the lamina and petiole of mature winter leaf of Arum italicum Miller
No full textLaminae and petioles from mature winter leaves of Arum italicuM were studied in order to obtain information on the sun-shade intra-tissue properties of chloroplasts. This inference was based on the: (1) micro- and submicroscopic characteristics of the chloroplasts, (2) cytochemical localizations of functional PS I and PS II, (3) pigment patterns and compositions, (4) immunolocalization of Rubisco, and (5) net photosynthesis. It was inferred that all the chloroplasts across the lamina had adaptations to intermediate shade conditions, without a sun-shade dimorphism between the palisade and the spongy tissues. In the petiole, where normally-structured chloroplasts were surprisingly present in the entire thickness of the organ, a structural and chemical dimorphism was found between the outer chlorenchyma and the inner aerenchyma where intermediate shade-type and extreme shade-type chloroplasts were present, respectively. However, some anomalies in the pigment composition were noted chiefly in the inner enchyma (low concentrations of β-carotene and lutein, absence of zeaxanthin, presence of unusual pigments, for instance lutein epoxide, lutein cis-isomer, and chlorophyllide a). The Rubisco immunolabelling in the outer chlorenchyma of the petiole was similar to that in the lamina, while it was very scant in the inner aerenchyma. Net photosynthesis in the petiole was about 75% of that recorded in the lamina. These data suggest that the petiole of the mature winter leaf of A. italicum closely co-operates with the lamina for enhancing light capture and utilization
Risposte dell'apparato fotosintetico di una xantoficea nivale sottoposta a condizioni di buio prolungato.
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