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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of N-acetylcysteine on mucus trasnport velocity (MV), ciliary beat frequency (CBF), mucus production (MP), mucus lysis and on the micro-morphology of the secretory cells was studied in mammalian airways. The results showed that: 1. MV increased in healthy rats and rabbits, as well as in bronchitic rats, after concentrations as low as 10(-14) g/ml. Depression of MV occurred first at 10(-6) and 10(-5) g/ml in healthy and bronchitic animals, respectively. 2. CBF was stimulated at concentrations between 10(-12) and 10(-10) g/ml and decreased at concentrations above 10(-8) g/ml. 3. MP increased by approximately 100% over control values. 4. Lysis of stagnant mucus was evident first at a concentration of 10(-11) g/ml after 15 min incubation. 5. TEM confirmed the increased activity of the mucus secreting cells and showed that no pathological changes occurred within the cell following incubation at 10(-7) g/ml for up to 150 min. The importance of these findings on the overall mucociliary function is discussed.
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PMID:N-Acetylcysteine and mucociliary activity in mammalian airways. 58 Mar 87

Scanning and transmission electron microscopy (SEM and TEM) revealed unique structures and development of the venomous spicules of tussock moth caterpillars of the genus Euproctis: (1) Flower-like structure at the distal end and a longitudinal minute depression on the proximal subapical wall of these spicules were observed by SEM. This depression was revealed to be a small hole by TEM. (2) During molting, observed were cytoplasmic processes of several trichogen cells penetrating the cytoplasm of a tormogen cell to form the spicules with the holes at their subapical portions. A papilla was formed by a tormogen and several epidermal cells. (3) After the molting, the cytoplasmic process in a spicule disappeared and the spicule cavity was replaced by electron-dense materials secreted apparently from the trichogen cell. (4) It was considered that the electron-dense materials were the main toxic or precursory substances in the Euproctis spicules.
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PMID:Studies on the venomous spicules and spines of moth caterpillars. I. Fine structure and development of the venomous spicules of the Euproctis caterpillars. 73 32

We examined the morphodifferentiation of subneural apparatuses at neuromuscular junctions with scanning and transmission electron microscopy (SEM and TEM) in the sternothyroid muscle of postnatal rats. As evidenced with SEM, primitive synaptic troughs found at birth were smooth cup-like depressions 5-6 micron in diameter. At the 5th postnatal day, low sarcoplasmic ridges appeared in the depression which successively grew and upheaved to remodel the depression into anastomosed gutters during the next 10 days. Subneural apparatuses attained almost the adult form by the 30th day, though synaptic troughs were smaller in size and exhibited a less complex pattern. At birth, the depression contained a few mostly pit-like or elongated oval invaginations:incipient junctional folds. By the 15th day, junctional folds rapidly developed, resulting in about an 18-fold increase in number per endplate with the parallel differentiation of slit-like junctional folds of adult form. At the 30th day, junctional folds were mostly slit-like, though pits still coexisted in a small proportion. As a shape factor, we measured the ratio of the length of the folds to their maximum width (L/W); the folds with L/W less than 2 were defined as pits, those with 2 less than or equal to L/W less than 5 as short slits, and those with L/W greater than or equal to 5 as long slits. At birth, pits occupied about 67% of the total number of the folds per endplate, which decreased to about 14% at the 30th day. Concomitantly, long slits remarkably increased from about 3 to 38%. Short slits increased from about 30 to 50% during the first 10 days but remained almost unchanged thereafter. The maximum L/W ratio was 12 at the 15th day and exceeded 20 after the 30th day. These quantitative data and the finding that pits were often closely associated with each other and also with a slit in a serial fashion indicate that the adjacent pits may fuse to each other and to the preformed slits. With TEM, a few incipient junctional folds were found at the 5th day, which extended into the subneural sarcoplasm with a depth less than 0.4 micron. At the 15th day, junctional folds increased both in number and in the maximum depth of about 0.8 micron. There also occurred a number of basal lamina-containing vacuoles identical in many respects to the transversely sectioned profiles of incipient junctional folds.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Formation and maturation of subneural apparatuses at neuromuscular junctions in postnatal rats: a scanning and transmission electron microscopical study. 310 Mar 62

Titania is of potential interest as an ultraviolet (UV) radiation blocking material in personal care products because of its excellent UV light absorption properties. Its high photocatalytic activity, however, facilitates the generation of reactive oxygen species, which can oxidize and degrade other ingredients during its formulation, raising safety concerns. Dense coating of titania nanoparticles with a silica layer could help in depression of their photocatalytic activity by disturbing the formation of radicals produced by the reaction of oxygen and/or water with the electron-hole pair. Depression of the high photocatalytic activity of titania necessitates that the silica shell has to be thick, with minimum microporosity. Coating parameters were optimized to attain greater amounts of precipitated silica and thicker shells with lower microporosity, which in turn resulted in great depression of photocatalytic activity. Silica-coated titania nanoparticles were characterized by TEM, XPS, FT-IR, EDX, and microporosity measurements. The photocatalytic activity was evaluated for the coated powder to investigate the efficiency of the silica coating as well.
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PMID:Control of silica shell thickness and microporosity of titania-silica core-shell type nanoparticles to depress the photocatalytic activity of titania. 1669 69

The high molecular weight (MW) polyethylene (PE) particles of particle size varied from macro to micron to nanometer were synthesized by Grignard reagent. The microscopy analysis (scanning electron microscope, SEM; transmission electron microscope, TEM; and atomic force microscope, AFM) shows the spherical shape of PE particles. The effects of particle size, varies from macro to nanometer scale on crystal structure, crystallinity (chic), glass transition temperature (Tg), melting temperature (Tm), surface roughness and mechanical properties were studied. Differential scanning calorimetry (DSC) experiments show that the nanoparticles of PE are highly crystalline (chic approximately equal 72%). The crystal length of PE nanoparticles is found to be approximately 14 A. Although the Gibbs-Thomson equation is explained the depression of melting temperature (DeltaTm) by 5 degrees C, the impervious results of Tg are still not fully understood. The low roughness value (2 A) proves the presence of "atomic-scale-chain" folding at the surface of PE nanoparticles. A novel protocol is developed, and the elastic modulus of individual nanospherical PE particles is computed from 'force-distance' mapping curves of AFM. Hemispherical tungsten (W) tip was fabricated from focused ion beam and used as an indenter to measure the mechanical properties. It is found that the nano sized PE particles have higher elastic modulus (E = 1.2-1.4 GPa) compared to the bulk or macro sized PE (E = 0.6-0.7 GPa). The results corroborate the robustness of our experiments, since, the analogous results for macro sized particles match well with the literature.
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PMID:High molecular weight polyethylene nanospheres: synthesis physical and mechanical properties. 1868 Oct 57

Clautriavia is a genus of uncertain taxonomic affinity that was initially described as gliding cells with one prominent trailing flagellum and a mid-ventral groove. The genus has been classified either with euglenids on the basis of similar paramylon-like granules or with cercozoans, specifically Protaspis spp., on the basis of general similarities in cell morphology and behavior. We isolated and cultivated a novel species of Clautriavia, namely C. biflagellata n. sp., from marine sand samples collected from the west coast of Vancouver Island, Canada and characterized this isolate with high resolution microscopy (LM, SEM, and TEM) and small subunit (SSU) rDNA sequence. The gliding cells of C. biflagellata n. sp. were round to oval in outline (12-20 microm wide and 15-20 microm long), dorsoventrally flattened, and capable of engulfing other eukaryotic cells (e.g., diatoms). The cells possessed two recurrent flagella of unequal length that emerged from a subapical pit within a ventral depression: the longer prominent flagellum was about 2X the cell length; the shorter flagellum was inconspicuous and was confined to the ventral depression. Molecular phylogenetic analyses demonstrated that C. biflagellata n. sp. branched strongly within the Cercozoa, but was only distantly related to Protaspis spp. Instead, C. biflagellata n. sp. branched closely with the recently established Auranticordida clade, consisting of Auranticordis quadriverberis and Pseudopirsonia mucosa. This position was concordant with our ultrastructural data, which demonstrated several features shared by A. quadriverberis and C. biflagellata n. sp. that are not present in Protaspis spp.: (1) a dense distribution of pores on the cell surface; (2) a distinct layer of muciferous bodies immediately beneath the cell surface; (3) a robust microtubular root attached to the anterior end of the nucleus; (4) the absence of a thick cell covering; and (5) the absence of conspicuously condensed chromosomes.
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PMID:Ultrastructure, life cycle and molecular phylogenetic position of a novel marine sand-dwelling cercozoan: Clautriavia biflagellata n. sp. 1988 Mar 48

Exposure to air pollution has been associated with acute myocardial ischemia, impaired myocardrial function, and ST-segment depression. Particulate matter (PM)-associated metals, especially vanadium and nickel, have been implicated in observed cardiovascular impairments. We aimed to assess the effect of single intratracheal pulmonary exposure to vanadium-rich respirable oil combustion PM (HP-10) on the intrinsic myocardial ischemic tolerance and mitochondrial integrity in rats. The authors subjected isolated heart tissue slices derived from saline or PM-exposed rats to low glucose low oxygen induced ischemia followed by oxygenated condition with glucose supplementation. Mitochondrial structural integrity was determined by TEM (transmission electron microscopy) and functionality by the 3-(4, 5 dimethylthiazol-2yl)-2, 5 diphenyltetrazolium bromide (MTT) assay. Rats exposed to PM exhibited no apparent inhibition of mitochondrial dehydrogenase activity in oxygenated conditions at 24 or 48 hr post-PM exposure. However, in conditions of simulated ischemia/reoxygenation, these heart slices showed a delayed but consistent and significant decrease in dehydrogenase activity compared to controls at 48 hr after exposure to PM. Electron microscopy revealed significant myocardial mitochondrial injury upon exposure to PM characterized by mitochondrial swelling and fusion. The authors conclude that exposure to soluble vanadium-rich PM induces mitochondrial functional impairment and structural abnormality, which compromises mitochondrial respiration and results in decreased tolerance to ischemia/reoxygenation in rats.
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PMID:Myocardial mitochondrial injury induced by pulmonary exposure to particulate matter in rats. 2254 75

Block copolymers form nanostructures that have interesting physical properties because they combine, for a single compound, the complementary features brought by each block. However, in order to fully exploit these properties, the physical state of each kind of domain must be precisely controlled. In this work, triblock PS-b-PEO-b-PS copolymers consisting of a central poly(ethylene oxide) (PEO) block covalently bonded to polystyrene (PS) blocks were synthesized by Atom Transfer Radical Polymerization. Their morphology was investigated by X-ray scattering and TEM experiments whereas their thermodynamic behavior was characterized by DSC. A strong decrease of both the melting temperature and the degree of crystallinity of PEO, due to its confinement between the PS domains, was observed and analyzed with a modified Gibbs-Thomson equation, following the approaches used for fluids confined in porous media. The existence of an amorphous bound layer, a few nanometers thick, at the PEO/PS interface, that does not undergo any phase transition in the temperature range investigated, accounts for both the melting temperature depression and the decrease of crystallinity upon confinement. This interfacial layer may significantly affect the mechanical and transport properties of these block copolymers that find applications as solid polymer electrolytes in batteries for example. Moreover, the value obtained for the solid PEO/liquid PEO surface tension is lower than those previously published but is thermodynamically consistent with the surface tensions of polymers at the solid/vapor and liquid/vapor interfaces.
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PMID:Effect of interfaces on the melting of PEO confined in triblock PS-b-PEO-b-PS copolymers. 2386 10

In this work, silver-doped TiO2 (Ag/TiO2) nanoparticles were synthesized using a photodeposition technique. The prepared Ag/TiO2 nanoparticles were characterized using TEM, SEM, XRD, and EDX techniques. The characterization of Ag/TiO2 nanoparticles using SEM and EDX techniques revealed the dispersion of Ag metal on the surface of TiO2. The photocatalytic activity of Ag/TiO2 and bare TiO2 in the presence of ultraviolet irradiation was investigated in the removal of chloramphenicol (CAP) as an antibiotic. CAP is a broad-spectrum antibiotic exhibiting activity against both Gram-positive and Gram-negative bacteria, as well as other groups of microorganisms. However, it is, in certain susceptible individuals, associated with serious toxic effects in humans including bone marrow depression, particularly severe in the form of fatal aplastic anaemia. The effects of the operational factors, such as doping content of Ag, photocatalyst dosage and calcination temperature were evaluated in the catalytic activity of Ag/TiO2. The results showed that the photocatalytic efficiency of TiO2 nanoparticles for the degradation of CAP, can be significantly improved by deposition an optimum amount of Ag nanoparticles (0.96 wt%) in the calcination temperature 300 degrees C. It was found that 900 mg/L of Ag/TiO2 is the optimum dosage in the removal of CAP with 20 mg/L initial concentration. The highest removal efficiency of CAP (-100%) at the optimum conditions was observed in 20 min. A mineralization study under optimum conditions showed about 88% reduction in total organic carbon after 120 min of irradiation time.
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PMID:Photocatalytic degradation of chloramphenicol in an aqueous suspension of silver-doped TiO2 nanoparticles. 2419 48

Nanosized TiO2 (n-TiO2), CeO2 (n-CeO2), and ZnO (n-ZnO) and bulk ZnO were chosen for a 4-h exposure study on a model ammonia oxidizing bacterium, Nitrosomonas europaea. n-ZnO displayed the most serious cytotoxicity while n-TiO2 was the least toxic one. The change of cell morphologies, the retardance of specific oxygen uptake rates and ammonia oxidation rates, and the depression of amoA gene expressions under NP stresses were generally observed when the cell densities and membrane integrities were not significantly impaired yet. The TEM imaging and the synchrotron X-ray fluorescence microscopy of the NPs impacted cells revealed the increase of the corresponding intracellular Ti, Ce or Zn contents and suggested the intracellular NP accumulation. The elevation of intracellular S contents accompanied with higher K contents implied the possible activation of thiol-containing glutathione and thioredoxin production for NP stress alleviation. The NP cytotoxicity was not always a function of NP concentration. The 200 mg L(-1) n-TiO2 or n-CeO2 impacted cells displayed the similar ammonia oxidation activities but higher amoA gene expression levels than the 20 mg L(-1) NPs impacted ones. Such phenomenon further indicated the possible establishment of an anti-toxicity mechanism in N. europaea at the genetic level to redeem the weakened AMO activities along with the NP aggregation effects.
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PMID:Short-term effects of TiO2, CeO2, and ZnO nanoparticles on metabolic activities and gene expression of Nitrosomonas europaea. 2571 Mar 20


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