AFDX-116 discriminates between muscarinic M2 receptors of the heart and the iris smooth muscle

Summary Studies with the atypical muscarinic antagonist pirenzepine provide convincing evidence for the classification of muscarinic acetylcholine receptors (mAChRs) into two subtypes, M₁ and M₂. The present study examines the heterogeneity of the M₂ subtype employing the newly developed competitive muscarinic antagonist, AFDX-116. Comparison of the binding affinities of pirenzepine, atropine, and AFDX-116 to mAChRs in microsomes from the rabbit cerebral cortex, heart, and iris smooth muscle shows that iris mAChRs, which are pharmacologically of the M₂ subtype, can be distinguished from M₂ cardiac receptors based on their affinity for AFDX-116. These results are consistent with the hypothesis that the M₂ receptor subtype consists of a heterogeneous population of receptors.Abbreviations mAChRs Muscarinic Acetylcholine Receptors - CCh Carbachol - NMS N-Methylscopolamine - AFDX-116 11-[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5,11-dihydro-6Hpyrido[2,3-b][1,4]benzodiazepine-6-one     

MAJOR CLADES OF THE ANGIOSPERMS

Abstract— Our knowledge of fundamental angiosperm interrelationships is still very incomplete. The absence of a narrowly circumscribed gymnosperm outgroup, ideally the sister group, makes character evaluation, necessary for a cladistic analysis, difficult. According to current views the superorder Magnoliiflorae with a number of other groups, for example the monocotyledons, may represent a complex of families near the base of the angiosperms. Interrelationships of groups within the monocotyledons are much better understood than those between groups within the dicotyledons. A cladogram of monocotyledon orders based on earlier work by R. Dahlgren, H. T. Clifford, and F. N. Rasmussen is presented. A data matrix for a sample of the angiosperms with 61 characters for 49 taxa, mostly magnoliifloran and related families, is presented. The characters are polarized mainly according to the current view that the primitive angiosperm morphotype is a woody dicotyledon with strobiloid flowers. As an alternative the matrix is adjusted following W. C. Burger's conjecture that the primitive angiosperm was a herbaceous monocotyledon with trimerous flowers. Both matrices were run in a computerized parsimony analysis, resulting in numerous equally parsimonious solutions. This result is illustrative of the great homoplasy in the available character information, and also of how little actually is known about fundamental angiosperm interrelationships or phylogeny.     

Assignment of orthologous relationships among mammalian alpha-globin genes by examining flanking regions reveals a rapid rate of evolution

In order to study the relationships among mammalian alpha-globin genes, we have determined the sequence of the 3' flanking region of the human alpha 1 globin gene and have made pairwise comparisons between sequenced alpha-globin genes. The flanking regions were examined in detail because sequence matches in these regions could be interpreted with the least complication from the gene duplications and conversions that have occurred frequently in mammalian alpha-like globin gene clusters. We found good matches between the flanking regions of human alpha 1 and rabbit alpha 1, human psi alpha 1 and goat I alpha, human alpha 2 and goat II alpha, and horse alpha 1 and goat II alpha. These matches were used to align the alpha-globin genes in gene clusters from different mammals. This alignment shows that genes at equivalent positions in the gene clusters of different mammals can be functional or nonfunctional, depending on whether they corrected against a functional alpha-globin gene in recent evolutionary history. The number of alpha-globin genes (including pseudogenes) appears to differ among species, although highly divergent pseudogenes may not have been detected in all species examined. Although matching sequences could be found in interspecies comparisons of the flanking regions of alpha- globin genes, these matches are not as extensive as those found in the flanking regions of mammalian beta-like globin genes. This observation suggests that the noncoding sequences in the mammalian alpha-globin gene clusters are evolving at a faster rate than those in the beta-like globin gene clusters. The proposed faster rate of evolution fits with the poor conservation of the genetic linkage map around alpha-globin gene clusters when compared to that of the beta-like globin gene clusters. Analysis of the 3' flanking regions of alpha-globin genes has revealed a conserved sequence approximately 100-150 bp 3' to the polyadenylation site; this sequence may be involved in the expression or regulation of alpha-globin genes.      

P48-Triggered transmembrane signaling transduction of human monocytes:mobilization of calcium ion and activation of protein kinase C(PKC)

INTRODUCTI0NThedifferentiati0nofcelIsalongthemonocyte-macr0phagepathwayandthesig-nalsinvo1vedinthesecel1sacquiringtheabilitytokilltum0rcellsarenotfllllyundersto0d.Wehavebeenstudingamoleculewhichappearst0beanimportantmemberofthecytokinenetworkinvo1vedintheregulati0nmonocyteactivation.ThiscytokinetermedP48wasisolatedfr0mthehllmannullcellleukemiacell1ineReh.IthasbeenpurifiedtohomogeneityandfOundtobedistinctfrominterferongamma,col0nystimulatingfactors(CSFs)andTNFalphaalldbeta[1,2].Func-ti…     

Glucose deprivation induces the selective accumulation of hexose transporter protein GLUT-1 in the plasma membrane of normal rat kidney cells

Antibody to the carboxyl-terminal of hexose transporter protein GLUT-1 was used to localize this carrier in normal rat kidney (NRK) cells during D-glucose (Glc) deprivation. Glc-deprivation of NRK cells induces increased hexose transport, inhibits the glycosylation of GLUT-1, and increases the content of both native, 55,000 apparent mol wt (Mr) and aglyco, 38,000 Mr GLUT-1 polypeptides. The distribution of GLUT-1 protein in subcellular fractions isolated from Glc-fed NRK cells shows that the 55,000 Mr polypeptide is most abundant in intracellular membrane fractions. Glc-fed cells that have been tunicamycin treated contain principally the 38,000 Mr GLUT-1 polypeptide, which is found predominantly in intracellular membrane fractions. In Glc-deprived cells the 55,000 Mr GLUT-1 polypeptide localizes predominantly in the Golgi and plasma membrane fractions, whereas the more abundant 38,000 Mr GLUT-1 polypeptide is distributed throughout all membrane fractions. In Glc-deprived but fructose-fed cells only the 55,000 Mr GLUT-1 polypeptide is detected, and it is found predominantly in the plasma membrane and Golgi fractions. The localization of GLUT-1 protein was directly and specifically visualized in NRK cells by immunofluorescence microscopy. Glc-fed cells show little labeling of cell borders and a small punctate juxtanuclear pattern suggestive of localization to the Golgi and, perhaps, endoplasmic reticulum. Glc-fed cells that have been tunicamycin treated show large punctate intracellular accumulations suggestive of localization to distended Golgi and perhaps endoplasmic reticulum. Glc-deprived cells exhibited intense labeling of cell borders as well as intracellular accumulations. Glc-deprived but fructose-fed cells show fewer intracellular accumulations, and the labeling is, in general, limited to the cell borders. Our results suggest that Glc deprivation induces the selective accumulation of GLUT-1 in the plasma membrane of NRK cells.     

Performance of a new dynamic model for predicting diurnal time courses of stomatal conductance at the leaf level

Under natural conditions, plants are subjected to continuous changes of irradiance that drive variations of stomatal conductance to water vapour (g_s). We propose a dynamic model to predict the temporal response of g_s at the leaf level using an asymmetric sigmoid function with a unique parameter describing time constants for increasing and decreasing g_s. The model parameters were adjusted to observed data using Approximate Bayesian Computation. We tested the model performance for (1) instant changes of irradiance; or (2) continuous and controlled variations of irradiance simulating diurnal time courses. Compared with the two mostly used steady‐state models, our dynamic model described daily time courses of g_s with a higher accuracy. In particular, it was able to describe the hysteresis of g_s responses to increasing/decreasing irradiance and the resulting rapid variations of intrinsic water‐use efficiency. Compared to the mechanistic model of temporal responses of g_s by Kirschbaum, Gross & Pearcy, for which time constants were estimated with a large variance, our model estimated time constants with a higher precision. It is expected to improve predictions of water loss and water‐use efficiency in higher scale models by using a small number of parameters.     

Genetic disruption of protein phosphatase 5 in mice prevents high-fat diet feeding-induced weight gain

The role of serine/threonine protein phosphatase 5 (PP5) in the development of obesity and insulin resistance associated with high-fat diet-feeding (HFD) was examined using PP5-deficient mice (Ppp5c^−/−). Despite similar caloric intake, Ppp5c^−/− mice on HFD gained markedly less weight and did not accumulate visceral fat compared to wild-type littermates (Ppp5c^+/+). On a control diet, Ppp5c^−/− mice had markedly improved glucose control compared to Ppp5c^+/+ mice, an effect diminished by HFD. However, even after 10 weeks of HFD glucose control in Ppp5c^−/− mice was similar to that observed in Ppp5c^+/+ mice on the control diet. Thus, PP5 deficiency confers protection against HFD-induced weight gain in mice.     

Cytochrome P450 enzyme activity in five herbivorous,non-passerine bird species

We examined hepatic cytochrome P450 activity in wild and hand-reared grey partridges (Perdix perdix), capercaillies (Tetrao urogallus) and ring-necked pheasants (Phasianus colchicus), as well as the enzyme activity in a variety of tissues of hand-reared Japanese quails (Coturnix coturnix japonica) and pigeons (Columba livia). Post-mortem decrease in hepatic enzyme activity in the grey partridge was measured. Hepatic 7-ethoxyresorufin-O-deethylase activity was similar in wild and hand-reared grey partridges and pheasants, but the activity was significantly lower in wild than in hand-reared capercaillies, probably resulting from their phenolic-rich diet. In the tissues of both quails and pigeons 7-ethoxycoumarin-O-deethylase exhibited the highest and 7-pentoxyresorufin-O-deethylase the lowest activity. Hepatic enzyme activity was significantly higher than that in other tissues. In the small intestine some activity could be found, reflecting some intestinal detoxication capacity. Enzyme activity decreased by 34-69% during the 30-min sampling period, which confirmed the importance of equalising sampling time to obtain comparable data. Because the hand-reared birds in this study were fed the same commercial diets, we assumed that the enzyme activity values detected reflect species differences without any induction by dietary secondary compounds.