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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Eimer's organ and adjacent structures and their changes after infraorbital axotomy was examined with LM, TEM and SEM in the Japanese shrew mole, Urotrichus talpoides. Approximately 3,000 of Eimer's organ covers the hairless snout tip of this animal. It protrudes to the corium from epidermis, and consists of column-shaped core and the cylindrical peripheral structures. About a dozen of naked fibers ascend vertically in the core; one or a few of them runs amidst the core and the others along its circumferential part. Each fiber has shelf-like endings one in each of 5 to 7 succeeding cells in the upper part of the core. At the uppermost part of the core structure is an opaque degenerating cell. Neurites were considered to grow up with the epidermal cells to which their endings are attached. This pattern of nerve ending was clearly observed for the first time in this study. Usually 3 Merkel cells lie at the base of an Eimer's organ contacting with a soup-plate-shape nerve terminal. In the dermis, an encapsulated corpuscle enveloping a nerve endings is found underneath each Eimer's organ. After axotomy, ipsilateral nerve fibers and their endings totally disappeared from Eimer's organ in a week. Perforation in the domes, flattening of the dome surface, and degeneration of the encapsulated corpuscles appeared on the transected side. In addition to this, several features of degeneration also appeared on the contralateral side. It might be considered as an effect of disuse from the disorders of the other side.
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PMID:Ultrastructure of the Eimer's organs of the Japanese shrew mole, Urotrichus talpoides (Insectivora, Mammalia) and their changes following infraorbital axotomy. 340 Aug 78

Izumenolide is a potent inhibitor of beta-lactamases, especially from Gram-negative bacteria. The I50 value of 0.01 microgram/ml for TEM-2 beta-lactamase, after 10 min preincubation, corresponds to a ratio of 7.6 moles inhibitor per mole of enzyme. The initial inhibitory reaction with TEM-2 beta-lactamase exhibits mixed reaction kinetics, suggesting a possible overlapping binding site with the active center. Tem-2 beta-lactamase is irreversible inactivated by izumenolide in a biphasic reaction. Carbenicillin offers partial protection against inactivation. Izumenolide exhibits limited antibiotic activity against some Gram-negative bacteria. Against beta-lactamase producing bacteria izumenolide provides protection to ampicillin and cephaloridine but the protection is limited due to permeability problems associated with izumenolide entry into the cells.
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PMID:Izumenolide-a novel beta-lactamase inhibitor produced by Micromonospora. II. Biological properties. 697 39

Low mole fractions of viral fusion peptides induce inverted cubic (Q(II)) phases in dipalmitoleoylphosphatidylethanolamine (DiPoPE), a lipid with unsaturated acyl chains that normally forms inverted hexagonal phase (H(II)) above 43 degrees C. The ability to form a Q(II) phase is relevant to the study of membrane fusion: fusion occurs in liposomal systems under conditions where Q(II) phase precursors form, and fusion may be an obligatory step in the lamellar (L(alpha))/Q(II) phase transition. We used X-ray diffraction and time-resolved cryoelectron microscopy (TRC-TEM) to study the effects of the influenza hemagglutinin fusion peptide on the phase behavior and structure of DiPoPE. X-ray diffraction data show that at concentrations of 3-7 mol%, the fusion peptide (FP) induces formation of a Q(II) phase in preference to the H(II) phase. TRC-TEM data show that the FP acts at early stages in the phase transition (i.e. within seconds): at 2-7 mol%, FP decreases or inhibits formation of the L(alpha)/H(II) intermediate morphology observed via TRC-TEM in pure DiPoPE at the same temperature. Our X-ray diffraction data imply that FP either does not affect, or slightly increases, the spontaneous curvature of the host lipid (i.e. either does not affect or tends to destabilize inverted phases, respectively). FP may act in part by affecting the relative stability of two intermediate structures in the phase transition mechanism, as suggested previously. These results indicate a new way in which hydrophobic sequences of membrane proteins may be fusogenic.
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PMID:Effect of influenza hemagglutinin fusion peptide on lamellar/inverted phase transitions in dipalmitoleoylphosphatidylethanolamine: implications for membrane fusion mechanisms. 1101 54

Colloidal dispersions of tungstic acid (H(2)WO(4)) have been prepared in water/(TX-100+alkanol)/n-heptane water-in-oil microemulsion media by reacting Na(2)WO(4) with HCl. The effects of alkanol chain length, TX-100/alkanol mass ratio, temperature, and dilution at different [water]/[TX-100] mole ratios (omega) have been studied by the dynamic light scattering technique. The formation of H(2)WO(4) in the microwater pool has been established by FT-IR measurements. The particle sizes and shapes in microemulsion media and in isolated states have been measured by TEM and SEM techniques. The enthalpy of formation of H(2)WO(4) in the water pool of the microemulsions has also been determined microcalorimetrically. Copyright 2001 Academic Press.
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PMID:Dispersed Molecular Aggregates. 1125 94

Pure goethite particles in the nanometer size range (from approximately 200 to approximately 80 nm) with an elongated shape (axial ratio from approximately 5 to approximately 8) useful as iron precursors for magnetic recording have been prepared by oxidation of the suspensions resulting from the addition of sodium carbonate to Fe(II) sulfate aqueous solutions under a restrictive set of experimental conditions (Fe(II) concentration, carbonate/Fe(II) mole ratio, temperature, and air flow rate). In all cases, the goethite particles were formed by a dissolution-recrystallization mechanism through an intermediate green-rust phase. The particle size was determined by the carbonate/Fe(II) ratio (which controls the formation pH), the FeSO(4) concentration, and the air flow rate. The smallest particles (length 80 nm) were obtained for a high carbonate/Fe(II) mole ratio (>/=3), a low Fe(II) concentration (0.075 mol dm(-3)), and an air flow rate of 2 dm(3) min(-1). The goethite particles were also characterized by the electron diffraction and high-resolution TEM finding that they were monocrystalline, having the crystalline c axis parallel to the longest particle dimension.
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PMID:Uniform nanosized goethite particles obtained by aerial oxidation in the FeSO4-Na2CO3 system. 1270 28

A new nanometer complex heteropoly acid with Keggin structure, H3PW12O40/SiO2, were prepared by sol-gel method, and were characterized with IR, UV, XRD and TEM techniques. By means of this nanometer catalytic materials, the optimum conditions of the n-butyl acrylate synthesis have been studied. The results show that the complex heteropoly acid H3PW12O40/SiO2 nanoparticles have the mean grain size of 40 nm and they are typical amorphous. A strong chemical interaction exists between H3PW12O40 and silica surface. The nanoparticles have high catalytic activity for synthesizing n-butyl acrylate. The optimum catalytic conditions are as follows: the mole ratio of acrylic acid and n-butyl alcohol is 1:1.2, the reaction temperature is approximately 90-96 degrees C, and the catalyst quantity in the reaction is 10% of the acid mass. The conversion proportion is 94.37% and product yield 91.2% in 5 h. Apparently, the unique structure of the Keggin anions and surface acid center and the high specific surface area and the pseudoliquid phase of H3PW12O40/SiO2 play an important role in the esterification reactions with the acid catalyst.
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PMID:[Catalytic application of synthesizing n-butyl acrylate by a new type nanometer complex heteropoly acid catalyst H3PW12O40/SiO2]. 1576 24

We report the combined effects of phospholipase C (PLC), a pronucleating factor, and apolipoprotein A-I (apo A-I), an antinucleating factor, in solutions of model bile. Results indicate that apo A-I inhibits cholesterol nucleation from unilamellar lecithin vesicles by two mechanisms. Initially, inhibition is achieved by apo A-I shielding of hydrophobic diacylglycerol (DAG) moieties so as to prevent vesicle aggregation. Protection via shielding is temporary. It is lost when the DAG/apo A-I molar ratio exceeds a critical value. Subsequently, apo A-I forms small ( approximately 5-15 nm) complexes with lecithin and cholesterol that coexist with lipid-stabilized (400-800 nm) DAG oil droplets. This microstructural transition from vesicles to complexes avoids nucleation of cholesterol crystals and is a newly discovered mechanism by which apo A-I serves as an antinucleating agent in bile. The critical value at which a microstructural transition occurs depends on binding of apo A-I and so varies with the cholesterol mole fraction of vesicles. Aggregation of small, unilamellar, egg lecithin vesicles (SUVs) with varying cholesterol composition (0-60 mol %) was monitored for a range of apo A-I concentrations (2 to 89 microg/mL). Suppression of aggregation persists so long as the DAG-to-bound-apo A-I molar ratio is less than 100. A fluorescence assay involving dansylated lecithin shows that the suppression is an indirect effect of apo A-I rather than a direct inhibition of PLC enzyme activity. The DAG-to-total apo A-I molar ratio at which suppression is lost increases with cholesterol because of differences in apo A-I binding. Above this value, a microstructural transition to DAG droplets and lecithin/cholesterol A-I complexes occurs, as evidenced by sudden increases in turbidity and size and enhancement of Forster resonance energy transfer; structures are confirmed by cryo TEM.
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PMID:Combined interaction of phospholipase C and apolipoprotein A-I with small unilamellar lecithin-cholesterol vesicles: influence of apolipoprotein A-I concentration and vesicle composition. 1588 68

The well-mixed copper-nickel nanoparticles were prepared when the molar ratio of Cu2+ to Ni2+ was 1:1 by simultaneous reduction of CuSO4 and NiCl2 with hydrazine in the microemulsion of SDS/n-butanol/n-heptane/water at 70 degrees C, and was characterized by TEM, ED, TGA, EDS, and XRD. ED analysis and XRD patterns suggest the formation of the homogeneous alloy structure in the bimetallic nanoparticles. Average size of the sample calculated from the full width at medium height of peak 111 in the XRD patterns using Scherrer formula is 5.53 nm. TEM photographs show a narrow distribution of Cu-Ni nanoparticles that essentially are monodispersed and the mean diameter is 12 nm. The results indicate that the composition and size of alloy nanoparticles depend on the mole ratio of H2O to SDS, the method of addition of Cu2+ and Ni2+, and the mole ratio of Cu2+ and Ni2+ in the initial precursor solution.
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PMID:Preparation of Cu-Ni alloy nanocrystallites in water-in-oil microemulsions. 1606 Dec 44

Melanosomes in retinal tissues of a human, monkey and rat were analyzed by EDX in the TEM. Samples were prepared by ultramicrotomy at different thicknesses. The material was mounted on Al grids and samples were analyzed in a Zeiss 912 TEM equipped with an Omega filter and EDX detector with ultrathin window. Melanosomes consist of C and O as main components, mole fractions are about 90 and 3-10 at.%, respectively, and small mole fraction ratios, between 2 and 0.1 at.%, of Na, Mg, K, Si, P, S, Cl, Ca. All elements were measured quantitatively by standardless EDX with high precision. Mole fractions of transition metals Fe, Cu and Zn were also measured. For Fe a mole fraction ratio of less than 0.1at.% was found and gives the melanin its paramagnetic properties. Its mole fraction is however close to or below the minimum detectable mass fraction of the used equipment. Only in the human eye and only in the retinal pigment epitelium (rpe) the mole fractions of Zn (0.1 at.% or 5000 microg/g) and Cu were clearly beyond the minimum detectable mass fraction. In the rat and monkey eye the mole fraction of Zn was at or below the minimum detectable mass fraction and could not be measured quantitatively. The obtained results yielded the chemical composition of the melanosomes in the choroidal tissue and the retinal pigment epitelium (rpe) of the three different species. The results of the chemical analysis are discussed by mole fraction correlation diagrams. Similarities and differences between the different species are outlined. Correlation behavior was found to hold over species, e.g. the Ca-O correlation. It indicates that Ca is bound to oxygen rich sites in the melanin. These are the first quantitative analyses of melanosomes by EDX reported so far. The quantitative chemical analysis should open a deeper understanding of the metabolic processes in the eye that are of central importance for the understanding of a large number of eye-related diseases. The chemical analysis also allows a correlation with structural changes observed at the various regions of the eye.
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PMID:Quantitative chemical analysis of ocular melanosomes in the TEM. 1636 48

Ce(IV)-loaded Y-zeolites (CeY) were prepared for selective removal of the trace amount of organic sulfur compounds from hydrodesulfurization (HDS)-treated diesel oil. The CeY samples can be obtained from NH4-Y-zeolite (NH4Y) using liquid-phase ion-exchange and solid-state ion-exchange methods. The ion-exchange reactions, structures, and selective adsorptions of organic sulfur compounds of the CeY samples were investigated using XRD, IR, XPS, TEM, and GC sulfur analyzer. The organic sulfur compound uptakes strongly depend on the amount and the valency of Ce in the zeolite structure. Ce(IV) shows much higher adsorptive ability than Ce(III). A CeY-S sample prepared by solid-state ion-exchange reaction of NH4Y and Ce(NO3)3 with Ce/NH4 mole ratio of 0.63 at 250 degrees C showed a maximum sulfur uptake from a model solution of HDS-treated gasoline containing thiophene [S = 5 ppm (ppm = mg/L)]. A desulfurization from a HDS-treated diesel oil containing organic sulfur compounds (S = 1.87 ppm) and H2S (S = 0.73 ppm) was investigated with a combination of the CeY-S and a CuO adsorbent for removal of H2S by a batch method. The sulfur content was reduced to below 0.01 ppm for the first time. This method provides a promising desulfurization process to prepare a clean fuel for fuel cells.
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PMID:Preparation of cerium-loaded Y-zeolites for removal of organic sulfur compounds from hydrodesulfurizated gasoline and diesel oil. 1645 14


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