The administrator at War

Landis, James M.

doi:10.4159/harvard.9780674435704.c9

Cited by 13 publications

(18 citation statements)

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“…Thus, there is now considerable evidence that also the composition and physico-chemical properties of the plasma or perfusate in contact with the endothelium is of greatest importance for normal capillary permeability, especially visavi macromolecules (e.g. Landis & Pappenheimer 1963, Areekul 39696, Rippe & Folkow 1977, Mason et al 1977, Diana et al 1980). Among 'plasma factors' influencing capillary permeability we will especially discuss the role of plasma proteins and also draw attention to the effect of adding neutral dextrans and FicoIP to plasma or a perfusate.…”

Section: Discussionmentioning

confidence: 99%

“…Firstly, as all the compared fractions of neutral and sulphate-substituted dextrans were dissolved in Krebs solution, the possibility arises that the complete absence of proteins in the perfusate during the relatively long periods of perfusion not only influenced the electrophysical properties but also the morphology of the capillary wall, as might be indicated by the extremely low U-values for all investigated dextrans, presented in the study (cf. Landis & Pappenheimer 1963, Rippe & Folkow 1977. Secondly, as the rabbit ear was always kept strictly isogravimetric, by adjustments of venous pressure, pre-and postcapillary resistances and intravascular volume varied between the different test situations, leading to small.…”

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confidence: 99%

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Capillary permeability to sulphate‐substituted and neutral dextran fractions in the rat hindquarter vascular bed

Haraldsson

Moxham

Rippe

1982

Acta Physiologica Scandinavica

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In order to investigate the impact of molecular charge on capillary permeability to macromolecules, capillary reflection coefficients (sigma) for various concentrations of two neutral dextran fractions (Mw 70 000 and 139 000) and one negatively charged, sulphate-substituted dextran fraction (Mw 109 000) were determined in the isolated perfused rat hindquarter preparation, during stable haemodynamic conditions. The capillary reflection coefficient was calculated as the ratio between the estimated colloid osmotic pressure in vivo, determined by an osmotic transient technique, and that in vitro, measured with an osmometer. Despite its intermediate size the sulphated dextran (D 109-S) showed a markedly higher sigma than the two neutral ones (D 70 and D 139) and, further, whereas sigma for D 70 and D 139 decreased with increasing dextran concentration, sigma for D 109-S remained constant over the whole range of concentrations investigated. At dextran concentrations equivalent to an in vivo colloid osmotic pressure of 23.5 mmHg, sigma averaged 0.901 for D 109-S, compared with 0.547 and 0.693 for D 70 and D 139, respectively, and with 0.87 for albumin in normal plasma. It is suggested that capillary macromolecular permeability is due to both structural and electrophysical properties of the microvascular barrier, where negative charges of the endothelial glycocalyx and of wall-adsorbed plasma proteins cause repulsion of circulating large polyanions.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Capillary permeability to sulphate‐substituted and neutral dextran fractions in the rat hindquarter vascular bed

Haraldsson

Moxham

Rippe

1982

Acta Physiologica Scandinavica

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“…vides a more informative view of the 2ostsynaptic specialization (Figs. 8, 10;Landis et al, 1987). In cerebellar Purkinje cell spines, the postsynaptic density appears to consist of very fine strands decorated with adherent, irregular globular proteins.…”

Section: Structure Of the Postsynaptic Densitymentioning

confidence: 99%

Membrane and cytoplasmic structure at synaptic junctions in the mammalian central nervous system

Landis

1988

J. Elec. Microsc. Tech.

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Application of rapid freezing, freeze substitution fixation, and freeze fracture techniques to the study of synaptic junctions in the mammalian central nervous system has revealed new aspects of synaptic structure that are consistent with and partially explicate advances in synaptic biochemistry and physiology. In the axoplasm adjacent to the presynaptic active zone, synaptic vesicles are linked to large spectrin-like filamentous proteins by shorter proteins that resemble synapsin I in morphology. This mesh of presynaptic filamentous proteins serves to concentrate synaptic vesicles in the vicinity of the active zone. The affinity with which the vesicles are bound by the mesh is probably modulated by the extent of phosphorylation at specific sites on the constituent filamentous proteins, and changes in the binding affinity result in changes in transmitter release. The structural organization of the postsynaptic density in Purkinje cell dendritic spines consists of very fine strands with adherent, heterogeneous globular proteins. Some of these globular proteins probably correspond to protein kinases and their substrates. The postsynaptic density, positioned at the site of the maximal depolarization caused by synaptic currents, apparently serves as a supporting framework for a variety of proteins, which respond to and transduce postsynaptic depolarization. At least two classes of filamentous protein fill the cytoplasm of spines with a complex mesh, which presumably contributes to maintenance of the spine shape. Membrane bound cisterns are a ubiquitous feature of Purkinje cell dendritic spines. Studies of rapidly frozen tissue with electron probe microanalysis and elemental imaging reveal that these cisterns take up and sequester calcium, which is derived from the extracellular space, and which probably enters the spine as part of the synaptic current.

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“…These systems included a Tekran 1130/1135 speciation unit coupled to a Tekran 2537A CVAFS. This combination, which is described in detail by Landis et al (2002) and Lindberg et al (2002), sequentially collects reactive gaseous mercury (RGM) on a KCl-coated annular denuder, fine particulate mercury (Hg-PM 2.5 ) on a regenerable particulate filter and gaseous elemental mercury (Hg o ) on gold traps. The collected Hg is thermally desorbed and analysed by the Tekran 2537A as Hg o .…”

Section: High-volume Tsp Samplermentioning

confidence: 99%

Mercury, Trace Elements and Organic Constituents in Atmospheric Fine Particulate Matter, Shenandoah National Park, Virginia, USA: A Combined Approach to Sampling and Analysis

Kolker

Engle

Orem

et al. 2008

Geostandard Geoanalytic Res

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Compliance with U.S. air quality regulatory standards for atmospheric fine particulate matter (PM2.5) is based on meeting average 24 hour (35 μ m−3) and yearly (15 μg m−3) mass‐per‐unit‐volume limits, regardless of PM2.5 composition. Whereas this presents a workable regulatory framework, information on particle composition is needed to assess the fate and transport of PM2.5 and determine potential environmental/human health impacts. To address these important non‐regulatory issues an integrated approach is generally used that includes (1) field sampling of atmospheric particulate matter on filter media, using a size‐limiting cyclone, or with no particle‐size limitation; and (2) chemical extraction of exposed filters and analysis of separate particulate‐bound fractions for total mercury, trace elements and organic constituents, utilising different USGS laboratories optimised for quantitative analysis of these substances. This combination of sampling and analysis allowed for a more detailed interpretation of PM2.5 sources and potential effects, compared to measurements of PM2.5 abundance alone. Results obtained using this combined approach are presented for a 2006 air sampling campaign in Shenandoah National Park (Virginia, USA) to assess sources of atmospheric contaminants and their potential impact on air quality in the Park. PM2.5 was collected at two sampling sites (Big Meadows and Pinnacles) separated by 13.6 km. At both sites, element concentrations in PM25 were low, consistent with remote or rural locations. However, element/Zr crustal abundance enrichment factors greater than 10, indicating anthropogenic input, were found for Hg, Se, S, Sb, Cd, Pb, Mo, Zn and Cu, listed in decreasing order of enrichment. Principal component analysis showed that four element associations accounted for 84% of the PM2.5 trace element variation; these associations are interpreted to represent: (1) crustal sources (Al, REE); (2) coal combustion (Se, Sb), (3) metal production and/or mobile sources (Mo, Cd, Pb, Cu, Zn) and (4) a transient marine source (Sr, Mg). Concentrations of Hg in PM2.5 at background levels in the single pg m−3 were shown by collection and analysis of PM2.5 on filters and by an automated speciation analyser set up at the Big Meadows air quality site. The speciation unit revealed periodic elevation of reactive gaseous mercury (RGM) that co‐occurred with peaks in SO2, indicating an anthropogenic source. GC/MS total ion current chromatograms for the two sites were quite similar indicating that organic signatures were regional in extent and/or that the same compounds were present locally at each site. Calculated carbon preference index values for n‐alkanes indicated that plant waxes rather than anthropogenic sources, were the dominant alkane source. Polycyclic aromatic hydrocarbons (PAHs) were detected, with a predominance of non‐alkylated, and higher molecular weight PAHs in this fraction, suggestive of a combustion source (fossil fuel or forest fires).

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The administrator at War

Cited by 13 publications

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Capillary permeability to sulphate‐substituted and neutral dextran fractions in the rat hindquarter vascular bed

Capillary permeability to sulphate‐substituted and neutral dextran fractions in the rat hindquarter vascular bed

Membrane and cytoplasmic structure at synaptic junctions in the mammalian central nervous system

Mercury, Trace Elements and Organic Constituents in Atmospheric Fine Particulate Matter, Shenandoah National Park, Virginia, USA: A Combined Approach to Sampling and Analysis

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