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  • Chemistry  (11)
  • Organic Chemistry  (4)
  • Rat epididymis  (3)
  • sediment  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 425 (1993), S. 77-81 
    ISSN: 1432-2013
    Keywords: Rat epididymis ; Hypoosmotic swelling ; Ca2+ store ; Osmoregulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Microfluorimetric studies were carried out to investigate the effects of hypoosmotic swelling on intracellular Ca2+ concentration ([Ca2+]i) in single rat epididymal cells. In Ca2+-free solution containing 50 μmol/l ethylenebis(oxonitrilo)tetraacetate (EGTA) hypoosmotic swelling (−160 mosmol/l) induced a transient rise in [Ca2+]i which was either monophasic, biphasic or oscillatory. The [Ca2+]i responses to repeated hypoosmotic stimulations followed a decremental pattern. However, if 2.5 mmol/l Ca2+ was admitted during the recovery period between successive stimulations, the second and the third [Ca2+]i responses were slightly greater than the first. Increasing the change in osmolarity from −14±1.0 to −154±1.5 mosmol/l increased the rise in [Ca2+]i but reduced the [Ca2+]i response to subsequent ionomycin stimulation (4 μmol/l). The swelling- and the ionomycin-induced rises in [Ca2+]i followed a reciprocal pattern. It was suggested that intracellular Ca2+ release in response to cell swelling in the epididymal epithelium might play a role in cell volume regulation and the control of epididymal fluid osmolarity.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2013
    Keywords: Rat epididymis ; Cl− secretion ; Cell culture ; Calcium ; cAMP ; α- and β-adrenergic agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A study was carried out to investigate the short-circuit current (I sc) response to noradrenaline (NA) and the signal transduction mechanisms involved in cultured rat cauda epididymal epithelium. In normal Krebs-Henseleit solution, NA (10 μmol · l−1) added basolaterally elicited a biphasic I sc response consisting of a transient spike followed by a second sustained response. The biphasic response was almost abolished by removing ambient Cl−. Preloading the tissues witha cell-permeant Ca2+ chelator, 1,2-bis(2-aminophenoxy) eth-ane-N,N,N′,N′,-tetraacetic acid acetoxymethyl ester (BAPTA/AM), or pretreating them with thapsigargin (Tg), a microsomal adenosine triphosphatase inhibitor abolished the initial spike in the I sc response to NA, but had little effect on the second component. Pretreating the tissues with a non-selective β-antagonist, nadolol, reduced the second I sc response in a dose-dependent fashion but the initial spike was not affected. Microfluorimetric studies showed that NA (100 μmol · l−1) elicited single Ca2+ spikes in isolated epididymal cells, which could be abolished by prior treatment with Tg. Biochemical assays showed that NA (10 μmol · l−1) increased intracellular cyclic adenosine monophosphate concentration ([cAMP]i) and the response was abolished by prior treatment with nadolol (50 μmol · l−1). The results showed that NA elicited a biphasic I sc response mediated by a rise in intracellular Ca2+ concentration ([Ca2+]i) followed by a rise in [cAMP]i. The Ca2+-mediated I sc response had a faster onset and more transient action than the cAMP counterpart. It is suggested that NA released from noradrenergic nerve endings regulates transepithelial Cl− secretion in the epididymis thereby providing the specialized millieu vital for sperm storage and maturation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 387 (1980), S. 61-66 
    ISSN: 1432-2013
    Keywords: Secretion ; Rat epididymis ; Ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It has been shown that the rat epididymis secretes proteins and organic compounds which may play a role in sperm maturation and storage. A method has been described to study caudal epididymal secretion in anaesthetized rats in vivo. The cauda epididymidis was luminally perfused with Krebs bicarbonate solution. The perfusate collected at the vas deferens was allowed to flow through a microcell and absorption at 280 nm was monitored and displayed on a recorder. Secretion as measured by this method was found to be independent of perfusion rate ranging from 2.8 to 25 μl/min and was maintained over a period of 8 h. Removal of Na+ ions from the perfusion fluid had no effect on the secretion rate. Removal of Ca2+ by perfusion of the duct with a Ca2+-free EGTA (1.5 mM) solution caused a rise in the secretion rate as revealed by an increase in absorption of the perfusate. High potassium produced similar results. Analysis of the perfusates showed that the Ca2+-free EGTA solution caused an increase in the secretion of non-protein materials whilst high potassium stimulated the release of proteins. Luminal application (0.5 mg/ml) or intraperitoneal injection (30 or 80 mg/kg) of cycloheximide had no effect on secretion during the 6 h posttreatment period. These results are discussed in relation to the possible mechanism of secretion in the epididymis.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 21 (1975), S. 1073-1080 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Application of Hildebrand's theory of the solubility of microsolutes in ordinary solvents, and of the Flory-Huggins theory to the solubility of steroids in polymers, has permitted the derivation of a predictive correlation between polymer permeability and steroid crystalline melting temperature, other correlating parameters being the entropy of fusion of the steroid and the (computed) solubility parameters of steroid and polymer. The correlation permits prediction of the permeability of any steroid in any polymer with reasonable accuracy.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 151-156 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Thermal diffusivity of high density polyethylene (HDPE) was studied over a wide range of temperatures (25 to 200°C) by melting powdered HDPE in a cylindrical mold at several pressures (101.3 to 5065 KPa gage) and recording the temperature profiles at several radial positions. The energy equation was solved numerically for cylindrical geometry. The thermal diffusivity of HDPE was fit as a function of temperature, porosity, and pressure.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 703-715 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: A series of copolymers containing styrene and a fluorocarbinol substituted styrene, vinyl benzyl hexafluorodimethyl carbinol, were prepared by substitution of hexafluoroacetone on polystyrene followed by hydrolysis, and by copolymerization of styrene and substituted styrene monomers. Sorption of dimethyl methyl phosphonate, DMMP, vapor in the copolymers was examined at 135°C by the piezoelectric sorption method and at 135 to 165°C by Inverse Gas Chromatography, IGC, and the results were analyzed by the Flory-Huggins equation. Both methods yield similar negative values of the Flory-Huggins Chi parameter at 135°C, and the Chi values are observed to become increasingly negative to -4.9 as the percent substitution of the aromatic rings In the copolymer is increased to 54 mole percent. A simplified thermodynamic analysis, based on experimental studies of the hydrogen bond formed between DMMP and hexafluoro-isopropanol, an analog of the fluoro-carbinol, through infrared spectroscopy and calorimetry at ambient conditions, is shown to predict the Chi dependency on copolymer composition observed at 135°C to within the accuracy of the experimental observations, however, the analysis predicts a decrease in Chi with increasing temperature that is too high relative to values observed by IGC at temperatures greater than 135°C.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 2 (1988), S. 427-433 
    ISSN: 0268-2605
    Keywords: Bioaccumulation ; alkyllead ; sediment ; mussels ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bioconcentration of alkyllead compounds from water and from contaminated sediments by freshwater mussels (Elliptio complanata) has been investigated. Higher levels of trimethyllead than triethyllead species are accumulated for the same exposure period. In-vivo transformation of the trialkyllead species by a series of dealkylation reactions giving dialkyllead and inorganic lead(II) species appears to take place. Rates of accumulation are higher for the more contaminated sediments.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 8 (1994), S. 385-391 
    ISSN: 0268-2605
    Keywords: Butyltin ; marinas ; Severn Sound ; Lake Huron ; Canada ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Severn Sound is a heavily used recreational and beating area in the southeast corner of Georgian Bay, Lake Huron, Canada. Because of the concern over the possible release of tributyltin species (TBT) from antifouling paints on boat hulls and marinas, surveys were carried out in 1989 and 1992 to determine the presence of this species and its degradation products dibutyltin (DBT) and monobutyltin (MBT) in this area. Many fish (pike and young-of-the-year spottail shiners) and sediment samples collected in 1989 contained detectable levels of TBT. A maximum concentration of TBT was recorded in northern pike in the spring to be 240 ng Sn g-1. Maximum levels occurred in marinas during the beginning of the boating season and significantly reduced during the summer and early autumn, although the maximum value of TBT in sediment (392 ng Sn g-1) was observed in the summer of 1989. The seasonal variation of TBT levels was further substantiated in the subsequent 1992 study, in which sediments from three areas in a marina were sampled at monthly intervals from May to October. TBT levels were much higher in May and then generally decreased with time. Mussels (Elliptio complanta) caged in the marina for three months also contained TBT. DBT was frequently detected in the sediments but less frequently in fish and mussels. MBT was generally below detection limits. Plants (macrophytes and cladophora) contained very small amounts of butyltin compounds.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 18 (1980), S. 85-88 
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 1 (1987), S. 235-239 
    ISSN: 0268-2605
    Keywords: Environment ; Transmethylation ; Alkyllead ; Alkyltin ; Methylarsenic compounds ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transmethylation reactions between organometals and metal ions in aqueous solutions in biotic and abiotic systems, with and without the presence of sediment, were investigated. It was found that alkyllead compounds can transfer their alkyl groups to Sn(II) and Sn(IV) ions to form various methyltin compounds in biotic and abiotic systems. The presence of sediment enhanced the transmethylation reactions. Methyltin compounds do not transfer their methyl groups of Pb(II). Methylarsenic acids transfer their methyl groups to Sn(II) and Sn(IV) in an abiotic system, but not in a biotic system containing sediment. The strong adsorption of tin onto sediment was the reason for the non-availability of tin ions for methylation. Methylarsenic acids do not transmethylate Pb(II). Other alkyllead compounds, such as ethyllead and butyllead species were also able to transfer their alkyl groups to tin. When both trimethyllead and triethyllead species are present in the same system, only the individual monoalkyl tin species were formed in both the Sn(II) and Sn(IV) solutions. No mixed alkyltin was produced. The findings of this study suggest that alkyllead compounds, if present in the environment, could be potential methylating agents for the formation of other methylmetals, such as methyltins. Methyltin compounds have already been documented to methylate mercuric ions in aqueous solution. Thus the study of transmethylation reactions opens up a new area of research that is essential in predicting the fate of organometals in the environment.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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