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  • 1
    ISSN: 1432-1424
    Keywords: Water pore sizes ; Water channels ; Reflection coefficients ; Selectivity filters ; Proximal kidney tubule ; Single file transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Proximal straight tubules (PST) were dissected from rabbit kidneys, held by crimping pipettes in a chamber and bathed in a buffered isosmotic (295 mOsm/kg) solution containing 200 mm mannitol (MBS). Changes in tubule diameter were monitored on line with an inverted microscope, TV camera and image processor. The PST were then challenged for 20 sec with MBS made 35 mOsm/kg hyperosmotic by addition of either NaCl, KCl, mannitol (M), glycerol (G), ethylene glycol (E), glycine (g), urea (U), acetamide (A) or formamide (F). With NaCl, KCl, M, G, E, g, U, and A, tubules shrunk osmometrically within 0.5 sec and remained shrunk for as long as 20 sec without recovering their original volume (sometimes A showed some recovery). PST barely shrunk with F and quickly recovered their original volume. The permeability coefficients were 0 μm/sec (NaCl, M, g, E and U), 1 μm/sec (A), 84 μm/sec (F) and 0.02 μm/sec (G). The reflection coefficients σ = 1.0 (NaCl, KCl, M, G, E, g and U), 0.95 (A) and 0.62 (F). Similar σ values were obtained by substituting 200 mOsm/kg M in MBS by either NaCl, KCl, G, E, g, U, a or F. The olive oil/water partition coefficients are 5 (M), 15 (U), 85 (A) and 75 (F) (all x10−5). Thus, part of F permeates the cell membrane through the lipid bilayer. The probing molecules van der Waals diameters are 7.4×8.2×12.0 (M), 3.6×5.2×5.4 (U), 3.8×5.2 ×5.4 (A) and (3.4×4.5×5.4 (F) Å. We conclude that only F clearly permeates the water channel (WCH). Water molecules must single file within the WCH. After subtraction of the bilayer permeability of the probes, we estimate for the WCH selectivity filter cross-section a diameter of 4.2–4.7 Å (if it is circular) and 3.6×4.2 Å (if it is rectangular). But if the oxygens facing the WCH lumen H bond with the molecules crossing the WCH, the WCH selectivity filter would be 3.3–3.8 Å (circular) and 3.6×4.0 Å (rectangular).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 148 (1995), S. 233-242 
    ISSN: 1432-1424
    Keywords: Paracellular flow ; Malpighian tubules ; Secretion ; Epithelial transport ; Water transport ; Convective flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Lumen to bath J 12/C 1 and bath to lumen J 21/ C 2 fluxes per unit concentration of 19 probes with diameters (d m) ranging from 3.0–30.0 Å (water, urea, erythritol, mannitol, sucrose, raffinose and 13 dextrans with d m 9.1–30.0 Å) were measured during volume secretion (J v ) in the upper segment of the Malpighian Tubule of Rhodnius by perfusing lumen and bath with 14C or 3H-labeled probes. J net=(J 12/C 1 − J 21/C 2) was studied as a function of J v · J v was varied by using different concentrations of 5-hydroxy tryptamine. J net for 3H-water was not different from J v We found: (i) A strong correlation between J net and J v for 8 probes d m =3.0–11.8 Å (group a probes), indicating that the convective component of J net is more important than its diffusive component and than unstirred layers effects which are negligible. Therefore group a probes are solvent dragged as they cross the epithelium, (ii) There is no correlation between J net and J v for 11 probes with d m=11.8–30 Å (group b). Therefore these probes must cross the epithelium by diffusion and not by solvent drag, (iii) In a plot of J net/J v vs. d m group a probes show a steep linear relation with a slope = −0.111, while for group b probes the slope is −0.002. Thus there is a break between groups a and b in this plot. We tried to fit the data with models for restricted diffusion and convention through cylindrical or parallel slit pathways. We conclude that (i) group a probes are dragged by water through an 11.0 Å-wide slit, (ii) Most of J v must follow an extracellular noncytosolic pathway, (iii) Group b probes must diffuse through a 42 Å-wide slit, (iv) A cylindrical pathway does not fit the data.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 45 (1993), S. 279-281 
    ISSN: 1432-1041
    Keywords: Rheumatoid arthritis ; Acetylator phenotype ; polymorphism ; sulphamethazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Acetylator phenotype has been determined with sulphamethazine (sulphadimidine) in 69 Spanish patients with rheumatoid arthritis (48 females), all of whom were on second line therapy, and in 96 age-matched normal controls (54 females). Thirty-two patients (46.4%) and 56 controls (58.3%) were classified as slow acetylators. On analysing separately the females in both groups, 37.5% of patients and 63% of controls were found to be slow acetylators. No difference was found in the males (patients 66.3% and controls 52.4% slow acetylators). Rapid acetylator phenotype may be a risk factor for the development of severe rheumatoid arthritis in women.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 7109-7115 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The nuclear magnetic resonance (NMR) spectra of the I=3/2 monovalent ions 23Na, 35Cl, 39K, and 79Br for NaCl and KBr dissolved into filamentous bacteriophage Pf1 solutions display line splittings and shifts consistent with an interaction between the nuclear spin and the electric field gradient produced by the Pf1 particles. The average electric field gradient and thus the spectral splitting for ions in the void space between magnetically aligned Pf1 particles is modeled using a numerical solution to the Poisson–Boltzmann equation. An NMR titration experiment in a 57 mg/mL Pf1 solution is used to determine the background Na+ ion concentration in solution as 32 mM which compares well with the 31.1 mM negative surface charge on Pf1. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0378-1119
    Keywords: Recombinant DNA ; antibiotic resistance ; macrolides ; transport
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 136 (1997), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The immunopathological mechanism of pemphigus foliaceus acantholysis remains controversial. Previous workers have found that IgG autoantibodies are reactive with the epidermal surface and capable of blister induction. The presence of complement components in lesions also suggests their potential role in this disease. Complement participation, however, has not been clearly demonstrated.We describe a case of pemphigus foliaceus (PF) in a 58–year old woman which was confirmed by histopathological and immunopathological studies, and by ELISA assay on recombinant PF antigen.Unusual features of this case include the predominance of IgG1 anti–epithelial antibody in both the deposits and circulation, and the preferential binding of IgG and complement component 3 at the upper epidermis. We believe that this pattern of co–localized deposition suggests a location–specific, non–random complement activation.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 1145-1148 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the structural and optical properties of Ge/Si self-assembled quantum dots epitaxially grown on Si(001). The Ge islands are grown in an industrial 200 mm single-wafer chemical vapor deposition reactor. The surface density of the Ge islands is as much as 2×1010 cm−2. The islands exhibit a maximum photoluminescence at 1.55 μm wavelength. The photoluminescence energy is correlated to the three-dimensional quantum confinement energy and to the size and geometry of the clusters, as observed by cross-section transmission electron microscopy. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 4262-4264 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous GeO2 has been grown by plasma assisted anodic oxidation at temperatures ≤100 °C. The growth kinetics can be explained in terms of a constant current anodization model. Infrared absorption spectroscopy has been used to characterize the transverse and longitudinal optic vibrational modes of the oxide network. Values are displaced with respect to bulk oxide due to geometrical optic effects and plasma induced network structure variation. In relaxed GeO2 we estimate the mean Ge-O-Ge bridging bond angle to be 〉123° and the full width at half peak height of the bond angle distribution is ∼14°. Electrical measurements on thin oxide capacitors suggest that in 25 nm oxides there are ≤2×1011 negative charges cm−2 and negligible interface state densities. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1156-1158 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the fabrication of bulk samples of photorefractive polymers using the injection molding technique. The photorefractive properties of these materials are evaluated by four-wave mixing and two-beam coupling experiments. Samples with good optical quality, high diffraction efficiency, and net optical gain are obtained. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2292-2294 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical and photoconductive fatigue of fast photorefractive polymers have been studied in a family of C60-sensitized polymer composites containing styrene-based chromophores with varying ionization potential. Changes in response time and in photoconductivity were studied for exposures up to 104 J/cm2. Increasing the chromophore ionization potential beyond that of the polyvinylcarbazole host was found to stabilize the response time. Studies of the electric-field dependence of the steady-state diffraction efficiency in various samples confirm the role of C60 anions as possible traps. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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