Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0276640 (TEM)
 20,729 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Samples of human semen frozen in liquid nitrogen ( - 196 degrees C) with no glycerol, 5 and 10% glycerol were compared with samples that were untreated, with 10% glycerol but not frozen, and spermatozoa frozen at -20 degrees C. SEM and TEM of the samples indicates that 10% glycerol caused fewer surface changes of the spermatozoa than other treatments. Motility counts after the various freezing treatments were also highest when 10% glycerol was used as the cryoprotectant. Nonetheless, cryopreservation is detrimental to spermatozoa and often causes considerable damage to the acrosome with a leakage of the acrosomal contents.
 ...
PMID:Surface structure of spermatozoa frozen for artificial insemination. 88 75

Freeze-fracture provides a way of opening up cells and tissues for an internal view of cytoplasm and nucleus, and can give an internal view of a cytoplasmic organelle if the plane of fracture cuts through the organelle. Selective removal of soluble or other components is necessary for a deep view of structure at the fracture face. This may be achieved by osmium digestion, or by glycerol extraction, or by delaying fixation until after freeze-fracture and thawing, or by prior treatment with detergent to remove cell membranes and wash out soluble components. Cells may also be ruptured at room temperature, or in certain cases prepared to expose the inner surface of the plasma membrane for scanning electron microscopy (SEM) viewing. The problems and potential of SEM viewing of the cell interior are in certain respects similar to those encountered and derived from TEM replica study of freeze-fractured cells after deep etching. TEM replicas give better resolution, while SEM offers advantages in study of surfaces with considerable depth of structure. Study of fresh material, without fixation or alcohol dehydration, by rapid freezing and deep etching, is increasing our understanding of the artifacts that can be produced by these two preparative steps which are essential to critical point drying, whether used as a preparative step for SEM or for whole-mount high-voltage TEM microscopy.
 ...
PMID:Contribution of scanning electron microscopy to viewing internal cell structure. 676 49

To elucidate abnormalities in the renal microvasculature that could account for the functional disturbances occurring in two well-established models of acute renal failure, we gave rats a single intramuscular injection of glycerol (50%, 10 ml/kg) or daily subcutaneous doses of gentamicin (100 mg/kg/day). Afferent arteriolar diameters were determined by measuring methacrylate vascular casts with SEM. The filtration barrier was examined by both SEM and TEM. The EF area was quantitated. By 3 hr, the glycerol treatment markedly decreased PADs and DADs (PAD 19.1 to 12.0 micrometers, DAD 13.8 to 7.4 micrometers, p less than 0.05). The changes were similar for both inner and outer cortical regions. By 3 days the vasoconstriction was alleviated; however, renal failure persisted. At that time, however, EF area was decreased to 43% of normal. After 10 days of gentamicin treatment, only minimal vasoconstriction occurred in the outer cortex; however, EF area was decreased to a similar degree as observed with the 3-day glycerol-treated animals. There are two phases to glycerol-induced acute renal failure. The first phase (described as readily reversible) is characterized by intense vasoconstriction. The second phase, which is not immediately reversible, is associated with a decreased EF area. Smaller outer cortical afferent arterioles and a decreased fenestral diameter and density of the glomerular endothelium are seen only after gentamicin-induced renal failure is well established (after 10 days of treatment).
 ...
PMID:The morphology of the renal microvasculature in glycerol- and gentamicin-induced acute renal failure. 682 58

It has been postulated that phosphophoryn (PP) molecules bind specifically to type I collagen fibrils as the key event in inducing matrix mineralization in dentin. The nature and specificity of the collagen molecule-PP interaction has been examined by rotary shadowing-electron microscopy of mixtures of native, monomeric lathyritic rat skin collagen and purified rat incisor PP. An antibody to the amino-telopeptide of the collagen alpha1(I)-chain was used to determine the N-terminal end of the collagen molecules. Solutions of collagen and PP in 0.01 M ammonium formate (+/- antibody) were mixed and spread in 70% glycerol-30% 0.01 M ammonium formate on freshly cleaved mica surfaces using the sandwich technique. After rotary shadowing with Pt and backcoating with a carbon film, the spreads were viewed in a JEOL 1200EX TEM. The PP appeared as 15-nm diameter globules, the collagen as semi-flexible 270 nm filaments. At neutral pH and low PP/collagen mixing ratios, a single interaction site was evident, centered at approximately 210 nm from the N-terminus. The binding interaction induced a local conformational change in the collagen, bending the molecule and reducing its effective length. The sequence within the collagen-PP-binding domain has a net-positive charge but contains both positively and negatively charged groups.
 ...
PMID:Type I collagen-phosphophoryn interactions: specificity of the monomer-monomer binding. 984 70

Lamellar lyotropic liquid crystalline (LLC) systems are thermodynamically stable, optically isotropic systems, which are formed with low energy input. New possibilities for the development of controlled drug delivery systems are inherent in these systems due to their stability and special skin-similarly structure. The present aim was to formulate multicomponent LLC systems with a relatively low surfactant content, composed of materials official in the European Pharmacopoeia 4th. Polarizing light microscopic examination of the samples was carried out, together with TEM observation of replicas produced by freeze-fractured technique for the purpose of demonstrating the presence of lamellar LC domains. Our LLC samples contained: Brij 96 (poly-oxyethylene-10-oleyl ether) with water, liquid petrolatum (LP) and glycerol in a given concentration range. The interlamellar repeated distance (d(L)) confirming the existence of a regular structure was determined by means of X-ray diffraction. The d(L) and G'values of the samples changed according to a maximum curve with increasing glycerol concentration up to 40% (w/w). A prolonged drug release was observed in case of the very water-soluble ephedrine hydrochloride and the same phenomena was observed in the case of tenoxicam, which is practically insoluble in water.
 ...
PMID:Structure and drug release of lamellar liquid crystals containing glycerol. 1269 15

Self-assembling nanostructures were prepared from novel cationic amphiphilic compounds synthesized from vernonia oil, a natural epoxydized triglyceride. The presence of a 12,13-epoxy group on the C18 unsaturated fatty acid, vernolic acid, which is the main constituent of vernonia oil, permitted the synthesis of novel amphiphilic derivatives with a hydrogen-bonding hydroxyl and a cationic headgroup moiety on adjacent carbon atoms. The amphiphiles were prepared in a two-stage synthesis that comprised opening of the epoxy groups with a haloacetic acid, followed by quaternization of the halo group with a tertiary amine containing a C12 aliphatic chain. Intact vernonia oil as the starting material gave a triple-headed cationic amphiphile, containing three vernolic acid derived moieties connected through a glycerol backbone. A single-headed amphiphile with two alkyl chains and a single quaternary ammonium headgroup was synthesized from the methyl ester of vernolic acid as the starting material. The triple-headed derivative could form nonencapsulating structures. Cholesterol was required in the formulation (1:1) to make spherical vesicles that could encapsulate a water-soluble marker. The single-headed derivative, however, formed spherical encapsulating vesicles without cholesterol. TEM, NMR, and FT-IR were used to characterize the vesicles, and molecular structure vs morphology relationships were postulated on the basis of these data. The triple-headed amphiphile also formed a DNA complex that was highly resistant to hydrolysis by DNase. This amphiphile-DNA complex was used as vector for gene transfer in cell culture demonstrating efficient DNA transfection.
 ...
PMID:Novel cationic amphiphilic derivatives from vernonia oil: synthesis and self-aggregation into bilayer vesicles, nanoparticles, and DNA complexants. 1608 64

In this study a new family of microgel particles is investigated which contain methylmethacrylate (MMA), ethylacrylate (EA), acrylic acid (AA), glycerol propoxytriacrylate (GPTA), and Emulsogen (Em). GPTA is a trifunctional crosslinking monomer, whereas Em is a polymerisable alcohol ethoxylate surfactant. TEM and PCS data reveal that the extent of microgel swelling originates from a pH-independent contribution (due to Em) as well as a pH-dependent contribution (due to AA). The major contribution to swelling comes from pH-independent swelling. Consideration of the equations governing particle swelling allows the effective pK(a) of the incorporated AA groups to be estimated. There is evidence of a shift of the pK(a) for the AA groups from 4.5 to ca. 9.5 when the microgel particles containing AA also contain Em. This suggests intraparticle hydrogen bonding between AA and ethylene oxide segments at low pH.
 ...
PMID:A new family of water-swellable microgel particles. 1625 95

Single phase bimetallic Au/Pd catalyst was prepared and characterised by TEM techniques. The high activity in the selective liquid phase oxidation of glycerol towards glycerate is unambiguously attributed to the synergistic effect of alloy.
 ...
PMID:Single-phase bimetallic system for the selective oxidation of glycerol to glycerate. 1676 48

Copolymers based on poly(ethylene glycol) bearing one or more lipid-mimetic anchors were mixed with glycerylmonooleate (GMO)-a lipid with nonlamellar propensity-to form bulk and particulate bicontinuous cubic phases in water. The particulate phase was obtained via a liquid precursor method. Three forms of copolymer/GMO mixtures were investigated-precursor dispersions in glycerol and bulk and particulate phases in water-by visual observations, dynamic light scattering (DLS), and cryogenic transmission electron microscopy (cryo-TEM). The bulk phases were found to very slowly develop a macroscopic appearance that can be associated with the bicontinuous cubic phase. They were prepared in a slight excess of water, which became opalescent in some of the preparations. Cryo-TEM investigation of the excess showed that vesicles and particles with a dense interior coexisted. The precursors were prepared as solutions in glycerol. The viscous liquid material was investigated by DLS. Diffusion coefficients and the corresponding hydrodynamic radii, ranging from about 10 to 30 nm, were calculated. The particles are presumably of a structure similar to that of conventional emulsion droplets with GMO in the interior and copolymer molecules in the outer regions. The particulate phase in water was obtained upon hydration of the liquid precursors. The dispersions were investigated by DLS and cryo-TEM. DLS revealed the formation of nanosized particles. The size was found to increase with increasing copolymer content for copolymers with only one lipid-mimetic anchor, whereas the opposite trend was observed for the formulations with copolymers bearing more than one lipid-mimetic anchor. The shape and interior of the particles were studied by cryo-TEM. It was found that most particles were globular. For some of the compositions, particles with a dense internal structure dominated. The texture of the internal structures was assigned to dispersed bicontinuous cubic or L3 phases. In other compositions, the interior seemingly consists of arrays of interlamellar attachments.
 ...
PMID:Particulate and bulk bicontinuous cubic phases obtained from mixtures of glyceryl monooleate and copolymers bearing blocks of lipid-mimetic anchors in water. 1685 45

The controlled production of ZnO nanoparticles within an amorphous silica matrix is achieved using a new methodology consisting of four stages. First, precursor zinc glycerolate nanoparticles are produced within reversed micelles of glycerol in heptane stabilized by the surfactant Aerosol-OT (bis-ethylhexyl sodium sulfosuccinate, AOT). The surface of these nanoparticles is then modified by exchanging AOT with bis-trimethoxysilyl-ethane (BTME). The surface-modified nanoparticles are copolymerized with tetramethoxysilane (TMOS) to provide a composite silica material, in which the nanoparticles are apparently dissolved, producing a uniform distribution of zinc in the silica matrix. Finally, the conversion of zinc to ZnO is achieved by heating the material at 700 degrees C, leading to a uniform dispersion of very small (<10 nm) ZnO particles within the amorphous matrix. The fluorescence spectrum of the ZnO particles within the matrix is blue-shifted, as expected from the strong quantum confinement achieved. The properties of the system at all stages in this synthetic process are monitored using TEM, XRD, fluorescence and FT-IR spectroscopy. Glycerol forms complexes with many metal ions, so the present procedure may be generalized to provide uniform distributions of metal ions and subsequently metal oxide nanoparticles in amorphous silica.
 ...
PMID:Controlled production of ZnO nanoparticles from zinc glycerolate in a sol-gel silica matrix. 1689 Feb 34


1 2 3 4 5 6 7 8 9 10 Next >>