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  • Life Sciences (General)  (78)
  • Aircraft Stability and Control
  • GENERAL
  • Inorganic Chemistry
  • 1995-1999  (93)
  • 1955-1959
  • 1995  (93)
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  • 1995-1999  (93)
  • 1955-1959
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  • 1
    ISSN: 0044-2313
    Keywords: Perfluorovinyl amine ; X-ray crystal structure ; nucleophile ; electrophile ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaktion von Perfluorvinyl-Morpholin und Perfluorvinyl-Pyrrolidin mit Nukleophilen und ElektrophilenEs wird die Umsetzung von monofunktionellen und bifunktionellen Nukleophilen sowie des Elektrophils FNO mit Perfluorvinylaminen mitgeteilt. Die Perfluorvinylamine CF=CF2 und CF=CF2 wurden mit Dimethylamin und Diethylamin in Gegenwart kleiner Mengen Wasser umgesetzt zu CHFC(O)N(CH3)2 (1), CHFC(O)N(CH3)2 (2), bzw. CHFC(O)N(C2H5)2 (3). Mit Perfluorvinylpyrrolidin und Perfluorvinylmorpholin ergibt Ethanolamin die cyclischen Produkte CHF (4) bzw. CHF (5). Die Reaktion der Vinylamine mit (CH3)3SiOCH2CF3 in Gegenwart katalytischer Mengen von CsF ergibt cis- (6) und trans- (7) CF=CF(OCH2CF3) sowie cis- (8) und trans-(9) CF=CF(OCH2=CF3). Das elektrophile FNO reagiert langsam mit Perfluorvinylpyrrolidin und Perfluorvinylmorpholin und schneller mit (CH3)3CCF=CF2 zu CF(NO)CF3 (10), CF(NO)CF3 (11) bzw. (CF3)CF(NO)CF3 (12). Die Einkristall-Röntgen-Analyse wird zur Klärung der Produkte der kontrollierten Hydrolyse der Sultone von Perfluorvinylpyrrolidin wie des Sulfonsäureanhydrids C(O)CF2OS(O)2OCF2C(O) (13) eingesetzt. Die Röntgenstruktur von Perfluorbernsteinsäure · Monohydrat (14), die durch Hydrolyse von Perfluorvinylpyrrolidin mit einem Überschuß an Wasser erhalten wurde, wird erstmals mitgeteilt.
    Notes: In this study, both monofunctional and bifunctional nucleophiles, as well as the electrophile FNO, are reacted with perfluorovinyl amines. The perfluorovinyl amines CF=CF2 and CF=CF2 have been reacted with dimethylamine and diethylamine in the presence of small amounts of water to give CHFC(O)N(CH3)2 (1), CHFC(O)N(CH3)2 (2), and CHFC(O)N(C2H5)2 (3). With perfluorovinyl pyrrolidine and perfluorovinyl morpholine, ethanolamine gives the cyclized products CHF (4) and CHF (5), respectively. Reaction of the vinyl amines with (CH3)3SiOCH2CF3 in the presence of catalytic amounts of CsF results in the formation of cis- (6) and trans- (7) CF=CF(OCH2CF3) and cis- (8) and trans- (9) CF=CF(OCH2CF3). The electrophile FNO reacts slowly with perfluorovinyl pyrrolidine and perfluorovinyl morpholine, and more rapidly with (CF3)3CCF=CF2 to give CF(NO)CF3 (10), CF(NO)CF3 (11) and (CF3)3CF(NO)CF3 (12), respectively. Single crystal X-ray analysis is used to confirm the identity of the product obtained from the controlled hydrolysis of the sultone of perfluorovinyl pyrrolidine as the sulfonic acid anhydride C(O)CF2OS(O)2OCF2C(O) (13). The X-ray crystal structure of perfluorosuccinic acid monohydrate (14), which is obtained when the perfluorovinyl pyrrolidine sultone is hydrolyzed in excess water, is also reported for the first time.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2011-08-24
    Description: The rapid loss of skeletal-muscle protein during starvation and after denervation occurs primarily through increased rates of protein breakdown and activation of a non-lysosomal ATP-dependent proteolytic process. To investigate whether protein flux through the ubiquitin (Ub)-proteasome pathway is enhanced, as was suggested by related studies, we measured, using specific polyclonal antibodies, the levels of Ub-conjugated proteins in normal and atrophying muscles. The content of these critical intermediates had increased 50-250% after food deprivation in the extensor digitorum longus and soleus muscles 2 days after denervation. Like rates of proteolysis, the amount of Ub-protein conjugates and the fraction of Ub conjugated to proteins increased progressively during food deprivation and returned to normal within 1 day of refeeding. During starvation, muscles of adrenalectomized rats failed to increase protein breakdown, and they showed 50% lower levels of Ub-protein conjugates than those of starved control animals. The changes in the pools of Ub-conjugated proteins (the substrates for the 26S proteasome) thus coincided with and can account for the alterations in overall proteolysis. In this pathway, large multiubiquitinated proteins are preferentially degraded, and the Ub-protein conjugates that accumulated in atrophying muscles were of high molecular mass (〉 100 kDa). When innervated and denervated gastrocnemius muscles were fractionated, a significant increase in ubiquitinated proteins was found in the myofibrillar fraction, the proteins of which are preferentially degraded on denervation, but not in the soluble fraction. Thus activation of this proteolytic pathway in atrophying muscles probably occurs initially by increasing Ub conjugation to cell proteins. The resulting accumulation of Ub-protein conjugates suggests that their degradation by the 26S proteasome complex subsequently becomes rate-limiting in these catabolic states.
    Keywords: Life Sciences (General)
    Type: The Biochemical journal (ISSN 0264-6021); Volume 307 ( Pt 3); 639-45
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  • 3
    Publication Date: 2011-08-24
    Description: Roots of the tomato (Lycopersicon esculentum, Mill.) mutant (diageotropica (dgt) exhibit an altered phenotype. These roots are agravitropic and lack lateral roots. Relative to wild-type (VFN8) roots, dgt roots are less sensitive to growth inhibition by exogenously applied IAA and auxin transport inhibitors (phytotropins), and the roots exhibit a reduction in maximal growth inhibition in response to ethylene. However, IAA transport through roots, binding of the phytotropin, tritiated naphthylphthalamic acid ([3H]NPA), to root microsomal membranes, NPA-sensitive IAA uptake by root segments, and uptake of [3H]NPA into root segments are all similar in mutant and wild-type roots. We speculate that the reduced sensitivity of dgt root growth to auxin-transport inhibitors and ethylene is an indirect result of the reduction in sensitivity to auxin in this single gene, recessive mutant. We conclude that dgt roots, like dgt shoots, exhibit abnormalities indicating they have a defect associated with or affecting a primary site of auxin perception or action.
    Keywords: Life Sciences (General)
    Type: Planta (ISSN 0032-0935); Volume 195; 4; 548-53
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  • 4
    Publication Date: 2011-08-24
    Description: This study was designed to determine whether freeze-dried and thermostabilized foods on a space shuttle contain adequate folate and to investigate any effects of freeze-drying on folacin. Frozen vegetables were analyzed after three states of processing: thawed; cooked; and rehydrated. Thermostabilized items were analyzed as supplied with no further processing. Measurable folate decreased in some freeze-dried vegetables and increased in others. Folacin content of thermostabilized food items was comparable with published values. We concluded that although the folacin content of some freeze-dried foods was low, adequate folate is available from the shuttle menu to meet RDA guidelines.
    Keywords: Life Sciences (General)
    Type: Journal of food science (ISSN 0022-1147); Volume 60; 3; 538-40
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  • 5
    Publication Date: 2011-08-24
    Description: The use of Green's function has played a fundamental role in transport calculations for high-charge high-energy (HZE) ions. Two recent developments have greatly advanced the practical aspects of implementation of these methods. The first was the formulation of a closed-form solution as a multiple fragmentation perturbation series. The second was the effective summation of the closed-form solution through nonperturbative techniques. The nonperturbative methods have been recently extended to an inhomogeneous, two-layer transport media to simulate the lead scattering foil present in the Lawrence Berkeley Laboratories (LBL) biomedical beam line used for cancer therapy. Such inhomogeneous codes are necessary for astronaut shielding in space. The transport codes utilize the Langley Research Center atomic and nuclear database. Transport code and database evaluation are performed by comparison with experiments performed at the LBL Bevalac facility using 670 A MeV 20Ne and 600 A MeV 56Fe ion beams. The comparison with a time-of-flight and delta E detector measurement for the 20Ne beam and the plastic nuclear track detectors for 56Fe show agreement up to 35%-40% in water and aluminium targets, respectively.
    Keywords: Life Sciences (General)
    Type: Radiation and environmental biophysics (ISSN 0301-634X); Volume 34; 3; 155-9
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  • 6
    Publication Date: 2011-08-24
    Description: The purpose of this study was to test the hypothesis that the reduction in plasma volume (PV) induced by resistance exercise reflects fluid loss to the extravascular space and subsequently selective increase in cross-sectional area (CSA) of active but not inactive skeletal muscle. We compared changes in active and inactive muscle CSA and PV after barbell squat exercise. Magnetic resonance imaging (MRI) was used to quantify muscle involvement in exercise and to determine CSA of muscle groups or individual muscles [vasti (VS), adductor (Add), hamstring (Ham), and rectus femoris (RF)]. Muscle involvement in exercise was determined using exercise-induced contrast shift in spin-spin relaxation time (T2)-weighted MR images immediately postexercise. Alterations in muscle size were based on the mean CSA of individual slices. Hematocrit, hemoglobin, and Evans blue dye were used to estimate changes in PV. Muscle CSA and PV data were obtained preexercise and immediately postexercise and 15 and 45 min thereafter. A hierarchy of muscle involvement in exercise was found such that VS 〉 Add 〉 Ham 〉 RF, with the Ham and RF showing essentially no involvement. CSA of the VS and Add muscle groups were increased 10 and 5%, respectively, immediately after exercise in each thigh with no changes in Ham and RF CSA. PV was decreased 22% immediately following exercise. The absolute loss of PV was correlated (r2 = 0.75) with absolute increase in muscle CSA immediately postexercise, supporting the notion that increased muscle size after resistance exercise reflects primarily fluid movement from the vascular space into active but not inactive muscle.
    Keywords: Life Sciences (General)
    Type: The American journal of physiology (ISSN 0002-9513); Volume 269; 3 Pt 2; R536-43
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  • 7
    Publication Date: 2019-07-13
    Description: Previous studies have indicated that acid-optimal cysteine proteinase(s) in the endosomal-lysosomal compartments, cathepsins, play a critical role in the proteolytic processing of endocytosed proteins to generate the antigenic peptides presented to the immune system on major histocompatibility complex (MHC) class II molecules. The presentation of these peptides and the expression of MHC class II molecules by macrophages and lymphocytes are stimulated by gamma-interferon (gamma-IFN). We found that treatment of human U-937 monocytes with gamma-IFN increased the activities and the content of the two major lysosomal cysteine proteinases, cathepsins B and L. Assays of protease activity, enzyme-linked immunosorbant assays (ELISA) and immunoblotting showed that this cytokine increased the amount of cathepsin B 5-fold and cathepsin L 3-fold in the lysosomal fraction. By contrast, the aspartic proteinase, cathepsin D, in this fraction was not significantly altered by gamma-IFN treatment. An induction of cathepsins B and L was also observed in mouse macrophages, but not in HeLa cells. These results suggest coordinate regulation in monocytes of the expression of cathepsins B and L and MHC class II molecules. Presumably, this induction of cysteine proteases contributes to the enhancement of antigen presentation by gamma-IFN.
    Keywords: Life Sciences (General)
    Type: FEBS letters (ISSN 0014-5793); 363; 2-Jan; 85-9
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  • 8
    Publication Date: 2019-07-13
    Description: PURPOSE. Lumican is a major proteoglycan of vertebrate cornea. This study characterizes mouse lumican, its molecular form, cDNA sequence, and chromosomal localization. METHODS. Lumican sequence was determined from cDNA clones selected from a mouse corneal cDNA expression library using a bovine lumican cDNA probe. Tissue expression and size of lumican mRNA were determined using Northern hybridization. Glycosidase digestion followed by Western blot analysis provided characterization of molecular properties of purified mouse corneal lumican. Chromosomal mapping of the lumican gene (Lcn) used Southern hybridization of a panel of genomic DNAs from an interspecific murine backcross. RESULTS. Mouse lumican is a 338-amino acid protein with high-sequence identity to bovine and chicken lumican proteins. The N-terminus of the lumican protein contains consensus sequences for tyrosine sulfation. A 1.9-kb lumican mRNA is present in cornea and several other tissues. Antibody against bovine lumican reacted with recombinant mouse lumican expressed in Escherichia coli and also detected high molecular weight proteoglycans in extracts of mouse cornea. Keratanase digestion of corneal proteoglycans released lumican protein, demonstrating the presence of sulfated keratan sulfate chains on mouse corneal lumican in vivo. The lumican gene (Lcn) was mapped to the distal region of mouse chromosome 10. The Lcn map site is in the region of a previously identified developmental mutant, eye blebs, affecting corneal morphology. CONCLUSIONS. This study demonstrates sulfated keratan sulfate proteoglycan in mouse cornea and describes the tools (antibodies and cDNA) necessary to investigate the functional role of this important corneal molecule using naturally occurring and induced mutants of the murine lumican gene.
    Keywords: Life Sciences (General)
    Type: Investigative ophthalmology & visual science (ISSN 0146-0404); 36; 11; 2296-303
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  • 9
    Publication Date: 2019-07-13
    Description: A novel organ culture system has been developed to study the regulation of statoconia production in the gravity sensing organ in Aplysia californica. Statocysts were cultured in Leibovitz (LI5) medium supplemented with salts and Aplysia haemolymph for four days at 17 C. The viability of the system was evaluated by examining four parameters: statocyst morphology, the activity of the mechanosensory cilia in the statocyst, production of new statoconia during culture and change in statoconia volume after culture. There were no morphological differences in statocysts before and after culture when ciliary beating was maintained. There was a 29% increase in the number of statoconia after four days in culture. Mean statocyst, statolith and statoconia volumes were not affected by culture conditions. The presence of carbonic anhydrase in the statocysts was shown using immunohistochemistry. When statocysts were cultured in the presence of 4.0 x 10(exp -4) M acetazolamide to inhibit the enzyme activity, there was a decrease in statoconia production and statoconia volume, indicating a role for this enzyme in statoconia homeostasis, potentially, via pH regulation. These studies are the first to report a novel system for the culture of statocysts and show that carbonic anhydrase is involved in the regulation of statoconia volume and production.
    Keywords: Life Sciences (General)
    Type: NASA-CR-204876 , NAS 1.26:204876 , Journal of Comparative Physiology A. Sensory, Neural and Behavioral Physiology; 177; 415-425
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  • 10
    Publication Date: 2019-07-13
    Description: 1. Humans may visually track a moving object either when they are stationary or in motion. To investigate visual-vestibular interaction during both conditions, we compared horizontal smooth pursuit (SP) and active combined eye-head tracking (CEHT) of a target moving sinusoidally at 0.4 Hz in four normal subjects while the subjects were either stationary or vibrated in yaw at 2.8 Hz. We also measured the visually enhanced vestibuloocular reflex (VVOR) during vibration in yaw at 2.8 Hz over a peak head velocity range of 5-40 degrees/s. 2. We found that the gain of the VVOR at 2.8 Hz increased in all four subjects as peak head velocity increased (P 〈 0.001), with minimal phase changes, such that mean retinal image slip was held below 5 degrees/s. However, no corresponding modulation in vestibuloocular reflex gain occurred with increasing peak head velocity during a control condition when subjects were rotated in darkness. 3. During both horizontal SP and CEHT, tracking gains were similar, and the mean slip speed of the target's image on the retina was held below 5.5 degrees/s whether subjects were stationary or being vibrated at 2.8 Hz. During both horizontal SP and CEHT of target motion at 0.4 Hz, while subjects were vibrated in yaw, VVOR gain for the 2.8-Hz head rotations was similar to or higher than that achieved during fixation of a stationary target. This is in contrast to the decrease of VVOR gain that is reported while stationary subjects perform CEHT.(ABSTRACT TRUNCATED AT 250 WORDS).
    Keywords: Life Sciences (General)
    Type: Journal of neurophysiology (ISSN 0022-3077); 74; 2; 624-32
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