Demonstration of the parity-violating energy difference between enantiomers.
(1/225)
Racemic mixtures of (+) and (-) sodium potassium tartrate, tris(1, 2-ethanediamine)cobalt(III), and tris(1,2-ethanediamine)iridium(III) molecules were crystallized, and the optical activities of the resulting crystalline materials, dissolved in water, were carefully measured to study the influence of the parity-violating energy difference in the crystallization process. Although no effect was found in the case of tartrate, enantiomeric excess appeared in the crystallization of the cobalt and iridium complexes. These investigations, performed in our laboratory, demonstrated the contribution of the parity-violating neutral weak current to the forces acting in molecules. (+info)
Modulation of monocytic cell activity and virus susceptibility during differentiation into macrophages.
(2/225)
A major component of innate immune responses relies on monocytes and macrophages, virus infection of which will pose a particular problem for immunological defense. Consequently, the monocytic cell differentiation pathway was analyzed in terms of cellular modulations therein and their relation to monocytotropic virus infection. Differentiation was characterized by down-regulation of CD14, MHC Ags, the monocytic SWC1 marker, and p53; concomitant up-regulation of the SWC9 macrophage marker, a putative porcine CD80 (detected with anti-human CD80 Ab), and acid phosphatase secretion were also characteristic. Elevated phagocytic and endocytic activities as well as endosomal/lysosomal acidification were identified as being important to the macrophage. In contrast, monocytes possessed high accessory activity. This was multifactorial, concomitantly requiring 1) high MHC Ag expression; 2) enzyme activity of esterase, peroxidase, myeloperoxidase, and 5' nucleotidase in preference to glucosidase, galactosidase, and glucuronidase; and 3) elevated capacity for spontaneous IL-1 production. Only with all parameters was efficient stimulation of Ag-specific lymphocytes possible. These results point to a continuous process during differentiation, involving inter-related characteristics linking the more accessory monocyte to the scavenger macrophage, both in vitro and in vivo. Of particular interest was how these characteristics related to monocytotropic virus infection, and how a particular virus could show a clear preference for the differentiating macrophages. Such results not only further our understanding of porcine immunology, but also provide evidence and a potential model for the determination and characterization of monocytotropic virus-host cell interactions. (+info)
Gastric emptying of organic acids in the dog.
(3/225)
Test meals of 300 ml. of six different organic acids were instilled into the stomach of six healthy mongrel dogs. Citric, acetic, propionic, lactic, tartaric and succinic acid were given in 50, 100, 150, and 200 mN concentrations. 2. During the emptying process, the gastric contents were aspirated and immediately re-instilled at 10 min intervals, and the following parameters were recorded: volume, concentration of the organic anion, pH, hydrogen ion concentration and osmolarity. 3. By multiple stepwise regression analysis, the combination of parameters which most effectively determines gastric emptying rate was found to be: concentration of the organic anion, followed by intragastric volume and number of previous test meals given on the same day. These three parameters appear in the equation for gastric emptying rate in which the individual characteristic of each acid is expressed by a constant. 4. Among the various acids, inhibition of emptying rate increases with rising number of carboxylic groups of the acid and its molecular weight. 5. After proximal gastric vagotomy, emptying rate of organic acids is independent of volume, and emptying approaches an exponential pattern. 6. A model for gastric emptying of organic acids with at least three different receptors is proposed: one for the structure of the organic acid, one for concentration and one for intragastric volume. (+info)
Effect of oral mexiletine on the cough response to capsaicin and tartaric acid.
(4/225)
BACKGROUND: The effect of the orally active local anaesthetic mexiletine on the cough response to two different tussive agents, a C-fibre ending stimulator capsaicin and a chemostimulant tartaric acid, was examined in normal subjects. METHODS: The cough threshold, defined as the lowest concentration of capsaicin (C(5)-CP) or tartaric acid (C(5)-TA) causing five or more coughs, and histamine induced bronchoconstriction were measured three hours after a single oral dose of 300 mg mexiletine or placebo in 14 normal subjects. RESULTS: Mexiletene in a mean (SE) serum concentration of 0.99 (0. 04) microg/ml significantly increased C(5)-TA from a geometric mean (SE) of 32.0 (1.27) mg/ml with placebo to 49.9 (1.34) mg/ml, but C(5)-CP did not differ significantly between treatment with mexiletine (12.2 (1.33) microM) and placebo (14.9 (1.23) microM). CONCLUSIONS: These results suggest that the cough response to capsaicin and tartaric acid may be mediated in part via different neural pathways. (+info)
Complexation ion-exchange chromatography of some metal ions on papers impregnated with Ti(IV)-based inorganic ion exchangers.
(5/225)
The chromatographic behavior of 40 metal ions is studied on titanium (IV) arsenate, titanium (IV) phosphate-, titanium (IV) molybdate-, titanium(IV) tungstate-, and titanium(IV) selenite-impregnated papers in 0.1M oxalic, citric, and tartaric acid as mobile phases. Similar studies are carried out on Whatman No. 1 papers for comparison. The ion-exchange capacity of these papers is determined, and their selectivity for different cations is discussed. The mechanism of migration is explained in terms of ion-exchange, precipitation, and adsorption. The prediction of elution sequence from RF values is also checked. The average Ri is found to be almost linearly dependent on the charge of the metal ions. The effect of the pKa of complexing acids on average RF values of 3d series metal ions is explained. A number of binary and ternary separations are achieved. (+info)
Candida tartarivorans sp. nov., an anamorphic ascomycetous yeast with the capacity to degrade L(+)- and meso-tartaric acid.
(6/225)
An undescribed anamorphic yeast species of ascomycetous affinity, for which the name Candida tartarivorans is proposed, was isolated from dried wine lees in Portugal using a selective medium with L(+)-tartaric acid as the sole source of carbon and energy. The single isolate (IGC 4854T) showed the following characteristics: sympodial holoblastic conidiogenesis, absence of asci with ascospores, a negative colour reaction with Diazonium Blue B, production of elaborate pseudomycelium and ability to grow with inositol as sole source of carbon. Analysis of the physiological data pointed to a close relationship with other inositol-assimilating taxa, namely the genera Arxula, Stephanoascus, Sympodiomyces, Zygoascus and selected Candida species. Comparative analysis of the D1/D2 variable domain of the 26S rRNA gene of all available sequences for ascomycetous yeasts showed that strain IGC 4854T did not match with any other species in the database. The closest relative was Candida auringiensis Santa Maria, but the two species differed in 24 nucleotide positions. A description of the new species is given. (+info)
A new biotyping scheme for Salmonella typhimurium and its phylogenetic significance.
(7/225)
A new, two-tier system for biotyping Salmonella typhimurium gives a finer and more reliable differentiation of strains than the Kristensen scheme and is capable of future extension by the addition of new types and new tests. Strains are allocated to a primary type (1-32) by their reactions in five primary tests with Bitter's xylose medium, meso-inositol, L-rhamnose, d-tartrate and m-tartrate. Subtypes are distinguished within the primary types by reactions in ten secondary tests, which include observations for flagella and type-1 (haemagglutinating) fimbriae. Full biotypes are designated by letters indicating the subtype reactions appended to the primary-type numbers. A series of 2030 strains of S. typhimurium collected from many different sources and countries during 53 years was classified into 19 of the 32 potential primary biotypes and into 144 full biotypes. Of the series, 14% (275) were non-fimbriate inositol-nonfermenting rhamnose-nonfermenting (FIRN) strain in primary biotypes 29-32. Most other strains were fimbriate and rhamnose fermenting. Observations on several series of cultures isolated from different human or animal sources in the same epidemic showed that the biotype characters of a strain were generally stable during its growth in the natural environment and in the unselective media used for isolation and storage. Most non-fermenting strains gave rise to fermenting mutants on prolonged incubation in the substrate-containing--and therefore selective--test medium, and false-positive results from this cause were avoided by making the definitive readings of tests after a short, carefully chosen period of incubation. A genealogical tree has been drawn to show how eighteen observed primary biotypes may have evolved from a presumed archetypal ancestor of biotype 1. (+info)
Aspartate transcarbamylase of Escherichia coli. Mechanisms of inhibition and activation by dicarboxylic acids and other anions.
(8/225)
The interactions of several dicarboxylic acids and monoanions with Escherichia coli aspartate transcarbamylase and with its catalytic subunit have been studied by ultraviolet difference spectroscopy and steady state kinetics, with the following major findings. 1. A variety of dicarboxylic acids compete with carbamyl-P for the active sites of unliganded catalytic subunit, with steric requirements very different from those important for competition with L-aspartate for the subunit/carbamyl-P complex. Competition with carbamyl-P is much reduced if the dicarboxylic acid has a positively charged amino group. Acetate and chloride also compete. 2. At pH 7, equal concentrations of lysine acetate and L-aspartate are equally effective in displacing the transition state analog N-(phosphonacetyl)-L-aspartate (PALA) from the active sites of the concentrations of L-aspartate and lysine acetate is constant, increasing the concentration of L-aspartate does not relieve inhibition of the enzyme by PALA (Collins, K.C., and Stark, G. R. (1971) J. Biol. Chem. 246, 6599-6605). Therefore, the L-aspartate/subunit complex, like the acetate/subunit complex, must be incapable of participating in the catalytic reaction. We conclude that the kinetic mechanism is ordered, in agreement with the recent findings of Wedler and Gasser (Wedler, F.C., and Gasser, F.J. (1974), Arch. Biochem. Biophys. 163, 57-68) and in disagreement with the interpretation of Heyde et al. (Heyde, E., Nagabhushanam, A., And Morrison, J.F. (1973) Biochemistry 12, 4718-4726)... (+info)