A comparison of the receptor constants of morphine and ethylketocyclazocine for analgesia and inhibition of gastrointestinal transit in the rat

The efficacies and dissociation constants of proposed mu and kappa receptor agonists (morphine and ethylketocyclazocine, respectively) were compared using the method of partial irreversible blockade (with buprenorphine) and Stephenson's theory of drug action. While there was good agreement between the dissociation constant (KA) of morphine in analgesia (3.3 x 10(-5) M) and in inhibition of gastrointestinal transit (1.1 x 10(-5) M), the KA of ethylketocyclazocine differed by an order of magnitude in these endpoints (3.2 x 10(-6) M and 6.7 x 10(-5) M, respectively). The efficacies of morphine were found to be similar for the two effects studied (4.23 and 5.26), while those for ethylketocyclazocine differed markedly (2.06 and 10.39). The fraction of receptors remaining unblocked after buprenorphine was consistent for the test but not for the agonist, indicating a different distribution of receptors for the two endpoints. Our results strongly suggest that morphine induces analgesia, and slows transit in the small intestine, through the same type of receptor. The same conclusion cannot be drawn for ethylketocyclazocine.     

Purification of human plasma fibronectin by double affinity chromatography on gelatin and heparin-Trisacryl

In this work the human plasma fibronectin was purified by affinity chromatography using a tandem column system. The first affinity column was filled with gelatin-Trisacryl whereas the second one contained heparin-Trisacryl. This double affinity chromatography demonstrated its high efficiency in term of purity and yield. Several analytical methods (electrophoresis, immunoelectrophoresis, F.P.L.C. and adhesion assay on cultured eucaryotic cells) evidenced in fact the high purity of the preparation as well as its biological behaviour in term of cell adhesion and spreading. The performances of the sorbents used facilitate the scaling up when large quantities of FNP are needed.     

Interaction of the organic anion 1-aniline 8-naphthalene sulfonate (ANS) with isolated rat hepatocytes

The interaction of ANS with rat hepatocytes in time was studied by fluorescence spectroscopy. The intercept of the first linear portion of the time curve of interaction showed a positive value over all the ANS concentration range employed. This value was maintained after cellular disruption by homogenization. It was affected by ionic strength, pH, and divalent cation in the incubation medium, all conditions affecting the cellular surface. These data suggest that this phenomenon might be a binding of the compound to the hepatocytes surface. Due to the time constant and its disappearance after cellular disruption the other slower component of the curve seems to correspond to a process of translocation across the membrane.     

A rapid,single leaf,nucleic acid assay for determining the cytoplasmic organelle complement of rapeseed and related Brassica species

Summary An assay is described whereby Eco RI restriction fragment length polymorphisms of mitochondrial and chloroplast DNAs can definitively identify cytoplasms of interest in Brassica crop development. Restrictable mitochondrial and chloroplast DNA is extracted from as little as 2–3 g and 0.5 g leaf tissue, respectively, and the donor plants are able to continue to develop in a normal manner. An unknown cytoplasm can be identified in three days, which is a considerable saving in time and labor compared to the several years required by traditional methods. The assay is very inexpensive and should be established as a routine procedure in laboratories involved in sexual or somatic Brassica hybrid production.     

The Changing Shape of Plant Cells: Transformations During Cell Proliferation

Shapes of ideal cells can be inspected for the dynamic, or gnomonic,feature of producing daughter cells of the same shape. Suchfeatures can be found for (a) elongating epidermal cells, (b)isdiametrically enlarging epidermal cells, (c) elongating parenchymatouscells and (d) parenchymatous cells enlarging in three dimensions.Since each cell passes through a series of changes to finallyassume the form of the parental cell, a gnomonic cell must passthrough a gnomonic sequence of shapes during the cell cycle.A model tissue composed of gnomonic cells has complete stabilityof form through subsequent generations. Each of six parameters of ideal cells can be inspected in realcells in order to evaluate the effects of deviations from theideal on the stability of tissue pattern. (1) Cell plates ofreal and ideal cells do not expand for one generation. (2) Theangles in vertices of real cells shift over three cell cyclesfrom 170.1° to 137.3° to 124.0°, values close tothe expected set of 163°, 133° and 120° (3) Cellplates of real cells are not perpendicular to the longitudinalaxis of the cell. (4) Real cells do not divide synchronouslyas do ideal cells. (5) Real cells do not divide equally in halfas do ideal cells. (6) Finally, ideal cells have the same durationof the cell cycle whereas real cells have cycle times inverselyrelated to the initial size of the cell. It appears that a population of meristematic cells do not adhereto the restrictions of ideal cells, and consequently a significantamount of variance of form is added at each generation. Thereare two compensating mechanisms, one to hold size variationin check and one to keep shape deviations under control. Becauseof the probabilistic nature of cell division, cells increasein volume at various rates while the cell edges of all cellsexpand at a constant rate, indicating that the latter is theprimary element of growth while facet area and cell volume increasein dimension only for accommodation. Cell shape, gnomonic cells, Aponogeton elongatus, Lupinus alba