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  • 1995-1999  (37)
  • 1950-1954  (1)
  • 1945-1949
  • Chemistry  (31)
  • Optic neuritis  (4)
  • temperature  (3)
  • 1
    ISSN: 1432-1920
    Keywords: Key words Magnetic resonance imaging ; Optic neuritis ; Multiple sclerosis ; Visual evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MRI of the optic nerves was obtained in 13 patients with acute optic neuritis and 13 with a previous optic neuritis (ON), assessed by clinical features, visual fields and visual evoked potentials. Results of the conventional short tau inversion recovery (STIR) sequence obtained with a short echo time (STE-STIR; 22 ms) were compared with those of a long echo time (LTE-STIR: 80 ms) sequence. The conventional STE-STIR sequence revealed lesions in the optic nerves in 78.5 % of acute and 58.8 % of previous ON. The LTE-STIR sequence showed abnormalities in 92.8 % of acutely symptomatic nerves and 94.1 % of nerves with previous ON. The optic nerve lesions appeared significantly longer with the LTE-STIR sequence than with the conventional STE-STIR sequences, in both acute and previous ON.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Optic neuritis ; Multiple sclerosis ; Visual evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MRI of the optic nerves was obtained in 13 patients with acute optic neuritis and 13 with a previous optic neuritis (ON), assessed by clinical features, visual fields and visual evoked potentials. Results of the conventional short tau inversion recovery (STIR) sequence obtained with a short echo time (STE-STIR; 22 ms) were compared with those of a long echo time (LTE-STIR: 80 ms) sequence. The conventional STE-STIR sequence revealed lesions in the optic nerves in 78.5% of acute and 58.8% of previous ON. The LTE-STIR sequence showed abnormalities in 92.8% of acutely symptomatic nerves and 94.1% of nerves with previous ON. The optic nerve lesions appeared significantly longer with the LTE-STIR sequence than with the conventional STE-STIR sequences, in both acute and previous ON.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 400 (1999), S. 129-140 
    ISSN: 1573-5117
    Keywords: fish ; energetics ; temperature ; feeding ; prey abundance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract I examined food consumption and growth of walleye larvae in extensive culture ponds using direct methods and a bioenergetics model, and compared my results with laboratory feeding and growth studies. Walleye showed a diel pattern of increasing gut fullness during daylight hours. Larvae exhibited lower maximum food consumption rates in the ponds than predicted from previous short-term laboratory feeding studies. Direct estimates and bioenergetics model estimates of daily food consumption in the culture ponds were in poor agreement and the discrepancy varied with respect to walleye size. Food consumption rates in the ponds were related to walleye size (direct estimates) or water temperature (bioenergetics model estimates) but not zooplankton abundance. Growth exceeded 0.10 g g−1 d−1 for all but one sampling interval and the maximum growth rate in the culture pond fish was double the maximum growth rate determined in the laboratory. Growth was positively related to pond temperature and negatively related to walleye mass, but was not significantly related to zooplankton abundance. Gross conversion efficiency was negatively related to walleye mass, positively related to zooplankton abundance and not related to temperature. Food consumption and growth of walleye larvae in the field may be food-limited at much lower prey abundances than previous laboratory research has suggested.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-2614
    Keywords: heparin ; anticoagulation ; cardiopulmonary bypass ; temperature ; normothermia ; hypothermia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Medicine
    Notes: Abstract Objective. With the practice of warm cardiopulmonary bypass (CPB) at our institution we have observed an apparent increase in heparin requirements. CPB temperature predictability affects pharmacokinetics and differences in drug metabolism can be expected. We hypothesized that heparin requirements would increase with increasing CPB temperature. Methods. Following Institutional Review Board approval, we reviewed the charts of 354 patients undergoing primary coronary artery bypass graft surgery. We recorded patient demographic data, CPB duration, heparin requirements, and temperature during CPB. CPB was conducted between 24 °C and 37 °C. The Spearman's correlation coefficient, Pearson chi-square, and rank-sum tests were used for data analysis. Results. Core temperature during CPB correlated with heparin requirements (r = 0.13, p 〈 0.02). However, CPB duration was shorter in warm patients than in cold patients (r = −0.455, p 〈 0.0001). Additional heparin requirements adjusted for duration of CPB (units/minute) were also significantly greater in the warm group (p = 0.018). Conclusions. Maintenance of adequate heparin anticoagulation during CPB is clinically important. Warm CPB patients required more heparin per minute than those undergoing cold CPB. More frequent assessment of anticoagulation and administration of additional heparin should be considered in patients undergoing warm CPB.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 400 (1999), S. 129-140 
    ISSN: 1573-5117
    Keywords: fish ; energetics ; temperature ; feeding ; prey abundance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract I examined food consumption and growth of walleye larvae in extensive culture ponds using direct methods and a bioenergetics model, and compared my results with laboratory feeding and growth studies. Walleye showed a diel pattern of increasing gut fullness during daylight hours. Larvae exhibited lower maximum food consumption rates in the ponds than predicted from previous short-term laboratory feeding studies. Direct estimates and bioenergetics model estimates of daily food consumption in the culture ponds were in poor agreement and the discrepancy varied with respect to walleye size. Food consumption rates in the ponds were related to walleye size (direct estimates) or water temperature (bioenergetics model estimates) but not zooplankton abundance. Growth exceeded 0.10 g g−1 d−1 for all but one sampling interval and the maximum growth rate in the culture pond fish was double the maximum growth rate determined in the laboratory. Growth was positively related to pond temperature and negatively related to walleye mass, but was not significantly related to zooplankton abundance. Gross conversion efficiency was negatively related to walleye mass, positively related to zooplankton abundance and not related to temperature. Food consumption and growth of walleye larvae in the field may be food-limited at much lower prey abundances than previous laboratory research has suggested.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the Cu2+ complexation by macrocycles 1 (4-[(l,4,8,11-tetraazacyclotetradec-1-yl)methyl]-benzoic acid) and 2 (N-propyl-4-[(1,4,8,11-tetraazacyclotetradec-1-yl)methyl]-benzamide) as well as by macrocycle 1 conjugated to bovine serum albumin (bsa) and to ribonuclease A (rnase) were studied by stopped flow techniques. For 1 and 2, the kinetics were followed in the mM range monitoring the d-d* absorption band of the Cu2+ complex. From the pH dependence of kobs, the rate law is v = [Cu2+] (kLH[LH] + kLH2[LH2]), where kLH and kLK2 are the bimolecular rate constants for Cu2+ with the diprotonated (LH2) and monoprotonated (LH1) form of the ligand, respectively. The values are kLH2 = 1.7(1) M-1s-1 and kLH = 2.3(1) 105 M-1s-1 for 1, and kLH2, = 0.28(9) M-1s-1 and kLH = 2.0(1) 105 M-1s-1 for 2. The kinetics of the Cu2+ incorporation into 1,2 and 1 conjugated to bsa and rnase, i.e., 3 and 4, respectively, were also followed using nitroso-R salt as a metal indicator in the μM range, i.e., under conditions typical for the ‘post-labeling’ technique to give radiolabeled monoclonal antibodies. In these cases, the reaction takes place between the 1:1 complex of Cu2+ with nitroso-R-salt and the macrocycle. At pH 6.5, the rates are very similar to each other indicating that the complexation properties of the macrocycle attached to a protein are not very different from those of the free ligand under comparable conditions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of tetra-N-alkylated 1,4,8,11-tetraazacyclotetradecanes have been synthesized and their complexation potential towards Ni2+ and Cu2+ studied. In the case of sterically demanding alkyl substituents, such as i-Pr, PhCH2, or 2-MeC6H4CH2, no metal complexes are formed, whereas for substituents such as Me, Et, and Pr, the metal ion is incorporated into the macrocycle. The spectroscopic properties of the Ni2+ and Cu2+ complexes in aqueous solution indicate that, depending on the sterical hindrance of the N-substituents, the complexes are either square planar or pentacoordinated. All these Ni2+ and Cu2+ complexes react with N3- to give ternary species, the stability of which have been determined by spectrophotometric titrations. The tendency to bind N3- decreases with increasing steric hindrance of the alkyl substituents. The X-ray studies of the Ni2+ complex with the macrocycle 11, substituted by two Me and two Pr groups, and that of the Cu2+ complex with the tetraethyl derivative 8 show that in the solid state, the metal ions exhibit square planar coordination with a small distortion towards tetrahedral geometry.
    Additional Material: 6 Ill.
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  • 8
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 14-membered tetraazamacrocyclic Ni2+ and Cu2+ complexes of 4 (1, 4, 8-trimethyl-11-[(2-methylthio)ethyl]-1, 4, 8, 11-tetraazacyclotetradecane), 5. (1, 4-dimethyl-8, 11-bis[2-(methylthio)ethyl]-l, 4, 8, 11-tetraazacyclotetradecane), and 7 (1, 4, 8, ll-tetrakis[2-(methylthio)ethyl]-1, 4, 8, 11-tetraazacyclotetradecane), with pne, two, and four methylthio-substituted pendant chains, respectively, and the Ni2+ complex of 6 (1, 4-dimethyl-8, 11-bis (2-methoxyethyl)-1, 4, 8, 11-tetraazacyclotetradecane), with two methoxy-substituted pendant chains, were synthesized and their chemistry studied with regard to modelling F430. Solution spectra in H2O, MeCN, and DMF indicate participation of the side chain in metal coordination when the donor group is a thioether, whereas no coordination with the metal ion is observed with the ether group. Similarly the X-ray structures of the thioether-containing compounds [Ni(5)](ClO4)2, [Cu(5)](ClO4)2, and [Cu(7)](ClO4)2 show a coordination number of 5, whereas that of [Ni(6)](ClO4)2 with ether pendant chains, shows a coordination number of 4. Cyclic voltammetry of these complexes in MeCN reveals that Ni2+ is reversibly reduced to Ni+ between -0.64 and -0.77 V vs. SCE, the potential being influenced by the nature and number of the pendant chains. At more negative potentials, the thioether is cleaved, whereby a thiol is formed; the thiol is then oxidized at ca. + 0.8 V vs. SCE, when a glassy carbon electrode is used, or at ca. 0 V vs. SCE at a dropping Hg electrode. No cleavage of the ether bond in [Ni(6)](ClO4)2 is observed under similar conditions.
    Additional Material: 6 Ill.
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  • 9
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Cu2+ and Ni2+ complexes of three reinforced tetraazamacrocycles, containing a piperazine subunit and one or two alkyl substituents at the other two N-atoms have been prepared and their structural properties studied. In solution, the Ni2+ complexes are square-planar and show no tendency to axially coordinate a solvent molecule or an N3- ion. In contrast, the Cu2+ complexes change their geometry depending upon the donor properties of the solvent, being square-planar in MeNO2 and pentacoordinate in DMF. They also easily react in aqueous solution with N3- to give ternary species with pentacoordinate geometry, the stabilities of which have been determined. In the solid state, the X-ray crystal structures of three Cu2+ complexes also show both geometrical arrangements, two having a square-planar, the other one a distorted square pyramidal geometry. The difference behavior of Ni2+ and Cu2+ stems from the fact that the structural change from square-planar to square-pyramidal can easily be accomplished for Cu2+, whereas, for Ni2+, it is accompanied by an electronic rearrangement from the low-spin to the high-spin configuration. The relatively rigid ligands cannot Adapt to the somewhat larger high-spin Ni2+ion.
    Additional Material: 5 Ill.
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  • 10
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 14-membered macrocyclic Ni2+ complexes of 1 and 2, with a methylthio pendant chain, and those of 3 and 4, with a methoxy pendant chain, have been synthesized and their chemistry has been studied. Solution spectra in H2O, MeCN, and DMF indicate no participation of the side-chain donor group in metal coordination. This is also the case in the solid state as shown by the X-ray structures of the Ni2+ complexes with 1 and 2, in which a tetrahedrally distorted square-planar geometry around the Ni2+ results by the coordination of the four N-atoms of the macrocycle. Cyclic voltammetry of these complexes in MeCN reveals that Ni2+ is reversibly reduced to Ni+ between -0.7 and -0.8 V vs. SCE. For the complexes with 1 and 2, the thioether bond is cleaved at more negative potentials, whereby a thiol group is formed. This thiol group is then oxidized at ca. +0.7 V vs. SCE, when a glassy C electrode is used, or at ca. 0 V vs. SCE at a dropping Hg electrode. No cleavage of the ether bond in the complexes with 3 and 4 is observed under similar conditions. Reduction of the Ni2+ complexes of 1 and 2 with Na-amalgam in DMF produces small amounts of methane only in the case of 1, indicating the importance of the proximity between the NiI centre and the MeS group.
    Additional Material: 5 Ill.
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