Different temperature sensitivity of endosomes involved in transport to lysosomes and transcytosis in rat hepatocytes: analysis by free-flow electrophoresis

Endocytosis at reduced temperature has been used to define and characterize endosome subpopulations. Thus, the temperature sensitivity of endosome subpopulations involved in transport to lysosomes and transcytosis in rat hepatocytes was analyzed applying endosome labeling in the isolated perfused rat liver with route-specific ligands in combination with temperature shift protocols. Free-flow electrophoresis (FFE) that separates membranes and organelles based on their surface charge was then applied to isolate functional endosomes. Using asialoorosomucoid (ASOR) and polymeric immunoglobulin A (pIgA) as specific ligands of the lysosomal and transcytotic route, respectively, two distinct endosome subpopulations along either pathway were separated by FFE. Upon a short (1-3 min) internalization at 37 degrees C, 125I-ASOR and fluorescein isothiocyanate (FITC)-pIgA were colocalized in common early endosomes. Following a 5-10 min chase of the ligands at 37 degrees C endosomes labeled with 125I-ASOR were separated from endosomes labeled with FITC-pIgA, indicative of two distinct late compartments along the lysosomal and transcytotic route. Internalization at 16 degrees C resulted in accumulation of both ligands in common early endosomes and, consequently, in inhibition of transport to lysosomes and transcytosis. When 125I-ASOR or 125I-pIgA were first chased into late compartments at 37 degrees C and the temperature was subsequently lowered to 16 degrees C, biliary secretion of 125I-ASOR-derived counts was arrested, while biliary output of 125I-pIgA continued. In summary, ASOR en route to lysosomes can be blocked in early as well as in late endosomes at 16 degrees C, while biliary secretion of pIgA cannot be prevented by temperature reduction once the ligand had been transferred from early to late compartments.     

Charakterisierung und katalytische Aktivität von Ni2+-ausgetauschten X- und Y-Zeolithen. II. Die Reduzierbarkeit des Ni2+ durch niedere Olefine und die Dimerisierungsaktivität der Ni2+-ausgetauschten Zeolithe

Characterization and Catalytic Activity of Ni²⁺ -X and -Y Zeolites. II. Reducibility of Ni²⁺ by Low Olefines and the Dimerization Activity of the Ni²⁺ -Zeolites The reducibility of Ni²⁺ in X and Y zeolites by hydrogen, but-1-ene, propene, and ethene is compared. The degree of reduction was determined after isothermal reduction and reoxidation by the TPR method. At 673 K on X zeolites the reducibility decreases in the order: H₂ > but-1-ene, propene > ethene. On Y zeolites an inversion takes place: but-1-ene, propene > H₂, ethene. The mechanism of reduction by olefins should be determined by an intermediate splitting off of a hydride ion as a reducing species. Such a mechanism explains the higher degree of reduction in the more acid Y zeolites. Assuming low valent nickel as an active center in ethen dimerization the induction period results from the reduction of Ni²⁺ ions.     

A study ofK + p elastic scattering and reactionK + p→K + pπ+π− at 70 GeV/c

Results are presented onK ⁺ p elastic scattering and on the reactionK ⁺ p→K ⁺ pπ⁺π^? at 70 GeV/c. For the elastic channel, we measured the total ((2.29±0.04)mb) and differentialdσ/dt cross sections. The reactionK ⁺ p→K ⁺ pπ⁺π^? has a total cross section of (470±23) μb and is shown to be dominated by diffractive dissociation processes. The contributions of the quasi-two-body channels $$K^ + p \to K*^0 (890)\Delta ^{ + + } (1,236)$$ and $$K^ + p \to K*^0 (1,430)\Delta ^{ + + } (1,236)$$ and of the Double-Pomeron Exchange (DPE) processes are estimated.     

Sous-Solutions de Problèmes aux Limites en Dimension 1

We consider a boundary value problem where is a maximal monotone operator in and E is a multivalued operator in ² with non decre asing resolvent. We introduce a condition on E which insures that the operator inL ¹ (0,1) associated to this problem has non decreasing resolvent, and caracterise the subsolutions of the problem. We give different examples of operatorsE satisfying this condition.     

Relationship of the crystal structure of γ-N,N-dimethylaminopropyl 2,2-diphenylpropionate hydrochloride to antimuscarinic activity

The title compound was synthesized, characterized by¹H nmr, and crystallized for x-ray crystallography. The antimuscarinic potency of the title compound was about equipotent to aprophen or atropine in inhibiting acetylcholine-induced contraction of guinea pig ileum (K _B =4.5 nM) and in inhibiting carbachol-stimulated release of-amylase from rat pancreatic acinar cells (K _i =1.4nM), and in inhibiting the binding of [N-methyl-³H]scopolamine to cerebral cortex (K _i =6.6nM). In the crystal, the O-C-C-C-N⁺ segment adopted a gauche-gauche configuration resulting in an N⁺O (carbonyl) distance of 5.001(9)Å, a distance comparable to that in aprophen. The ether oxygen atom is buried rendering it inaccessible for interaction with the muscarinic receptor. The carbonyl oxygen atom is exposed to the surface of the molecule and is readily accessible for intermolecular interactions. The similarity in biological activities of the title compound and aprophen is congruous with their similar N⁺O (carbonyl) distances.National Research Council Senior Associate, on leave from the Department of Organic Chemistry, Israel Institute for Biological Research, Ness Ziona, Israel.National Research Council Senior Associate, on leave from the Department of Pharmaceutical Chemistry, Hebrew University of Jerusalem, Jerusalem, Israel.     

EQUILIBRIUM MODELING OF PSEUDOMONAD AGGREGATION AND PARTITIONING TO DOLOMITE†

Bioremediation is a common treatment technology considered for the remediation of many toxic and hazardous waste sites. In order for this technology to be successfully implemented, the mobility and adhesion characteristics of the microorganisms must be understood. This study explored the surface and adhesion characteristics of two pseudomonads: Pseudomonas aeruginosa Olin and P. fluorescens rib:lux. In general, the Lewis acid/base character of these microorganisms dominated surface thermodynamics. In both cases partitioning to dolomite, a common mineral, was predicted to be greatest in the stationary phase. In the log growth and decay phases, the Lewis acid/base interaction energy was repulsive for both organisms. The stationary phase for both microbes exhibited a reversal of the Lewis acid/base energy to attractive. Although the magnitude of the various surface energy components differed between the microorganism, it is remarkable that the Lewis acid/base energy exhibited similar behavior.     

Structure and solvation properties of aqueous sulfobetaine micelles in the presence of organic spin probes: a Molecular Dynamics simulation study

Structural and mechanical-dynamical information on a micelle formed by 72 monomers of N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SB 3–12) in water solution have been obtained through Molecular Dynamics simulations. Additional simulations have been carried out to evaluate whether and to what extent the structural features of the micelle are affected by the presence of a spin probe, typically utilized for the experimental characterization of these, rather complex, systems. Results indicate that the micelle shows a spherical shape not heavily influenced by the presence of the probe which only produces a slight volume increase. Further analysis also indicates that the probe, although inducing scarce alterations at the micelle-solvent interface, heavily influences the micelle core which appears less stable (more fluctuating) and less hydrated. Finally, analysis of residence times of water indicate—in line with many previous studies—the presence of a dual population characterized by different interactions with micelle interior.     

Development and validation of a stability-indicating micellar electrokinetic chromatography method for the determination of ezetimibe in pharmaceutical formulations.

A micellar electrokinetic chromatography (MEKC) method was validated for the analysis of ezetimibe. The method was carried out on a fused-silica capillary (50 microm i.d.; effective length, 40 cm). The background electrolyte consisted of a 25 mM borate buffer and 25 mM anionic detergent SDS (pH 9.75)/methanol (90:10, v/v). The capillary temperature was maintained at 35 degrees C, the applied voltage was 30 kV; the injection was performed using a pressure mode at 50 mbar for 5 s, with detection at 232 nm. The method was linear in the range of 2-150 microg/mL (R2=0.9999). The specificity and the stability-indicating capability were proven through degradation studies, which also showed that there was no interference of the excipients. The limits of quantitation and detection were 2 and 0.41 microg/mL, respectively. The method was applied for the analysis of ezetimibe pharmaceutical formulations, and the results were compared to those of the liquid-chromatography method.