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  • Electronic Resource  (17)
  • Chemistry  (12)
  • Sodium dichromate  (3)
  • cloud point  (2)
  • 1
    Electronic Resource
    Electronic Resource
    The role of glutathione in the acute nephrotoxicity of sodium dichromate (1992)
    Springer
    Archives of toxicology 66 (1992), S. 646-651 
    Details
    ISSN: 1432-0738
    Keywords: Sodium dichromate ; Nephrotoxicity ; Glutathione ; Ascorbate ; Carbohydrate metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ascorbate treatment 30 min prior to sodium dichromate (20 or 30 mg/kg, s.c.) shows higher potency than that of glutathione (GSH) in protecting against both the metabolic disturbance and nephrotoxicity induced by dichromate. However, ascorbate treatment after 2 h of dichromate intoxication had no effect on dichromate-induced blood urea nitrogen (BUN) elevation 3 days after intoxication. In contrast, dichromate-induced glucosuria, which reached maximum levels at 3 days after treatment, was significantly decreased by GSH or N-acetyl cysteine (NAC) treatment, even if its administration was after 24 h of dichromate intoxication. Pretreatment with GSH depletors such as diethyl maleate (DEM) and buthionine sulfoximine (BSO) had no effect on dichromate-induced nephrotoxicity. GSH levels in the liver and kidney were not affected at 3 h after dichromate treatment. However, dichromate significantly increased tissue GSH levels with a marked increase in liver per kidney GSH ratio at 24 h after treatment, if food was withheld subsequent to dichromate treatment, indicating that GSH biosynthesis resulted from the accelerated protein breakdown. These results suggest that GSH-mediated dichromate reduction is not a kinetically favorable pathway in vivo; however, GSH plays an important role in protection against dichromate-induced nephrotoxicity. In addition, the cellular metabolism of dichromate in the early period after treatment is important in the pathogenesis of its nephrotoxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01981504
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  • 2
    Electronic Resource
    Electronic Resource
    Acute toxic effect of sodium dichromate on metabolism (1990)
    Springer
    Archives of toxicology 64 (1990), S. 644-649 
    Details
    ISSN: 1432-0738
    Keywords: Sodium dichromate ; Glycolysis ; Hyperglycemia ; Glycogenolysis ; Cyanosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of sodium dichromate on cellular metabolism was investigated. Intraperitoneal injection of sodium dichromate into the rat (20 or 40 mg/kg) caused significant increases in serum lactate, pyruvate, and creatinine concentrations within 15 min after intoxication. Severe hyperglycemia occurred thereafter, as a result of increased hepatic glycogenolysis, which was seen in the first 2 h after dichromate. However, liver glycogen was resynthesized in 24 h-fasted rats after glucose refeeding. Dichromate decreased serum total amino acids, with a consequent increase in blood urea nitrogen (BUN) concentration. Unlike HgCl2 (2 mg/kg, i.p.), As2O3 (5 mg/kg, i.p.), and KCN (5 mg/kg, i. p.), dichromate showed the largest metabolic disturbance only in the early period after treatment. In addition, dichromate produced cyanosis, which appeared during the period of the accelerated glycolysis and breakdown of creatine phosphate. Regardless of chemical species, only the hexavalent chromium compounds had an effect on the cellular metabolism. Trivalent chromium compounds had no effect at all. These results suggest that dichromate possesses a characteristic dual action on cellular metabolism, which might be related to its metabolic fate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974692
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  • 3
    Electronic Resource
    Electronic Resource
    Nephrotoxicity of sodium dichromate depending on the route of administration (1991)
    Springer
    Archives of toxicology 65 (1991), S. 537-541 
    Details
    ISSN: 1432-0738
    Keywords: Sodium dichromate ; Nephrotoxicity ; Hepatotoxicity ; Lipid peroxidation ; Phenobarbital
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A comparison of the effects of intraperitoneal and subcutaneous routes of administration of sodium dichromate on nephrotoxicity in rats was studied. Dichromate when injected subcutaneously (SC group) produced a higher degree of nephrotoxicity than when administered intraperitoneally (IP group). It caused severe progressive proteinuria followed by polyuria and glucosuria, reaching maximum levels at 3 days after treatment in the SC group, whereas it produced mild proteinuria without glucosuria in the IP group. The dose-dependent increases in blood urea nitrogen (BUN) and creatinine concentrations, shown in the SC group, were not observed in the IP group. However, between the two groups, there were no great differences in either the urinary excretion rate of chromium or the electrophoretic patterns of urinary protein in the day 1 urine specimens. Pretreatment of phenobarbital (PB) had no remarkable effect on the dichromate-induced nephrotoxicity. In contrast, it potentiated dichromate-induced hepatotoxicity, the indices of which were the elevation in serum alanine aminotransferase (ALT) activity and hepatic lipid peroxide formation. These results suggest that the dependence of dichromate-induced nephrotoxicity on the route of administration is related to the chemical forms of chromium reaching the kidney, and the necrotizing property of dichromate results from its metabolic fate in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01973713
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  • 4
    Electronic Resource
    Electronic Resource
    Physical Stability of Ethyl Diatrizoate Nanocrystalline Suspension in Steam Sterilization (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 569-574 
    Details
    ISSN: 1573-904X
    Keywords: nanocrystals ; submicron crystals ; suspensions ; steam sterilization ; physical stability ; surfactants ; cloud point ; ethyl diatrizoate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To study the effects of formulation variables on the physical stability of a submicron crystal (nanocrystal) suspension under steam sterilization conditions. Methods. Suspensions of ethyl diatrizoate nanocrystals were prepared by wet milling in the presence of the surfactant poloxamine 908. Particle size distribution and zeta potential were measured by photon correlation spectroscopy. Results. On heating, the mean particle size of the nanocrystal suspension remained essentially unchanged up to 110°C, the cloud point of the stabilizing surfactant, but increased significantly above that temperature. The increase in particle size was a result of particle aggregation rather than crystal growth. Adding a cloud point booster to the suspension significantly minimized the particle aggregation at high temperatures. The purity of poloxamine 908 and the tonicity agent and buffer salt used also affected the heat stability of the suspension, the latter agents apparently through altering the surfactant cloud point. Conclusions. The aggregation of the ethyl diatrizoate nanocrystalline suspension under steam sterilization conditions was a result of phase separation of the stabilizing surfactant at its cloud point. When formulated with a cloud point booster to prevent the phase-separation, the suspension maintained its physical stability under steam sterilization without any significant change in particle size distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018883431970
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  • 5
    Electronic Resource
    Electronic Resource
    Cloud Point of Nonionic Surfactants: Modulation with Pharmaceutical Excipients (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 562-568 
    Details
    ISSN: 1573-904X
    Keywords: nonionic surfactants ; cloud point ; cloud point boosters ; poloxamers ; poloxamines ; liquid formulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To determine the cloud point of a variety of nonionic surfactants and to search for means to raise the surfactant cloud point in liquid formulations. Methods. Cloud points of nonionic surfactants were determined visually in a water bath. Organic compounds, many of which have been used as pharmaceutical excipients, were tested initially for effect on the cloud point of poloxamine 908. Four effective cloud point boosters (CPBs) from different structural classes were further tested on additional surfactants. Results. A number of compounds can raise the cloud point of nonionic surfactants. These cloud point boosters are classified into two categories: nonionic and ionic. The nonionic CPBs include poly(ethylene glycols), propylene glycol, methanol, ethanol, isopropanol, and 2-hydroxypropyl-β-cyclodextrin. They are effective at molar concentrations. The ionic CPBs include anionic and cationic surfactants, charged phospholipids, long chain fatty acids, and bile salts. They are effective at millimolar concentrations. Conclusions. The cloud point of nonionic surfactants used in liquid formulations can be modulated through the proper choice of excipient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018831415131
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  • 6
    Electronic Resource
    Electronic Resource
    Identification of an atypical constitutent of a clandestine opiate (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 350-351 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An unusual morphine analog was extracted and separated from an opium-like sample. The high resolution mass spectrum of the unknown substance confirmed the empirical formula as C17H18O2NCl. Mass spectra and retention factor values in thin-layer chromatography of both unknown and authentic standards were compared, which lead to the identification of the unknown as β-chloromorphide.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200010511
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  • 7
    Electronic Resource
    Electronic Resource
    Comparison of rubber reinforcement using various surface-modified precipitated silicas (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 1741-1750 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The reinforcement of a natural rubber compound by various surface-modified precipitated silicas was compared. Compound physical properties were determined for two silicas differing in surface area and were used as controls to evaluate these silicas after surface modification by using either a bifunctional organosilane coupling agent (γ-mercaptopropyl-trimethoxysilane) or a new surface modification process. This new process is based on the in situ polymerization of organic monomers solubilized inside surfactant bilayers that are adsorbed onto the silica surface to afford silicas modified with styrene-butadiene and styrene-isoprene copolymers. Both surface modification processes afford materials that dramatically increase the compound cure rate, thereby significantly reducing T90 cure times, while also improving tensile properties, tear strength, abrasion resistance, and compression set of the cured compound. The silane-modified silica gives a higher flex-cracking resistance than do the silicas modified by the in situ polymerization of organic monomers, whereas these latter silicas significantly increase rebound resilience and offer greater overall improvements in rubber compound performance. The rubber compound physical properties obtained using the modified, higher surface area Hi-Sil® 255 silica are generally improved relative to those obtained using the modified Hi-Sil® 233 silica. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Graft copolymer of gelatin/butyl acrylate and its use in the dye transferring blank film (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 38 (1989), S. 2171-2182 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Butyl acrylate was graft copolymerized onto gelatin using ceric ammonium nitrate as redox initiator. A series of grafted products with various gelatin-to-butyl acrylate ratios were prepared. The molecular weight of the grafted side chains and the number of grafting sites were measured. The possible grafting sites on gelatin macromolecules were pointed out through amino acid analysis. The electron micrograph and DSC analysis showed that the grafted chain (PBA) and backbone gelatin were in separated phases. The graft copolymer was used in the receiving layer of the dye transfer blank film, and the photographic, dye transfer printing, and some physicomechanical properties were studied with satisfactory results.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070381202
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  • 9
    Electronic Resource
    Electronic Resource
    Effectiveness factor calculations for immobilized enzyme catalysts (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 879-888 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The steady state, nonlinear diffusion equations which describe reactions in constrained enzyme solutions are of great interest in many biological and engineering applications. As in other types of nonlinear differential equations, exact analytical solutions do not exist except in some simplified cases. In this paper, a general procedure is presented for solving numerically for the substrate concentration profile and effectiveness factor utilizing the transformation method suggested by Na and Na. Design correlations for enzyme solutions constrained within spherical membranes are included. The use of a unique definition of the Thiele Modulus in these charts permits the clear illustration of the effects of substrate concentration and external mass transfer resistances on the overall effectiveness factor for the catalyst particle.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260150505
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  • 10
    Electronic Resource
    Electronic Resource
    Structural study on poly(ether ether ketone ketone)-poly(ether biphenyl ether ketone ketone) copolymers (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 17 (1996), S. 117-122 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Structures of poly(ether ether ketone ketone)-poly(ether biphenyl ether ketone ketone) copolymers were studied by using small angle X-ray scattering and the one-dimensional electron density correlation function method. The results revealed that structures of the aggregated state of the copolymers depend closely on the biphenyl content (nb). When nb = 0.35, invariant Q, long period L, average thickness of crystal lamellae d̄, electron density difference ηc - ηa and degree of crystallinity Wc, x assume minimum values.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1996.030170207
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