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  • 1
    Electronic Resource
    Electronic Resource
    Propellanes. 91. Fragmentation mechanism of alcohols under isobutane chemical ionization. Highly stereospecific formation of [M-OH]+ ions from [4.3.3]propellane-8,11-diols (1987)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 109 (1987), S. 7325-7327 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00258a014
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  • 2
    Electronic Resource
    Electronic Resource
    Testing with growth hormone-releasing factor (GRF(1–29)NH2) and somatomedin C measurements for the evaluation of growth hormone deficiency (1986)
    Springer
    European journal of pediatrics 145 (1986), S. 485-492 
    Details
    ISSN: 1432-1076
    Keywords: GRF ; Growth hormone deficiency ; Somatomedin C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Growth hormone (GH) responses to GRF (1 μg/kg BW i.v.) were investigated. Comparison between GRF(1–40) and GRF(1–29)NH2 in 11 young adult volunteers gave identical results. One hundred and thirty-one children and adolescents (45 with idiopathic GHD) were tested with GRF (1–29)NH2. The maximal GH levels (max GH) in response to GRF during the 120 min test period were found suitable to characterize the response. In cases without GHD no correlation to age, sex and pubertal development was observed. A maximal GH level of above 10 ng/ml was found to be normal. In 3 out of 86 children without GHD (one with Turner syndrome; two with simple obesity) max GH fell short of 10 ng/ml, while 11 of 45 cases with GHD exceeded this margin. In GHD, max GH was inversely correlated with age. There was no difference in max GH between groups with or without perinatal pathology as a presumed cause of GHD. GH levels to GRF were positively correlated with maximal GH level during sleep in GHD, but not correlated with responses seen to insulin or arginine. The value of GRF testing for the confirmation of GHD is discussed in the light of other GH stimulatory tests and basal somatomedin C measurements. It is suggested that the combination of testing with GRF and the determination of a basal SmC level offers a safe and convenient way to diagnose GHD in clinically suspected cases, though in some cases further diagnostic tests may be needed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02429048
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  • 3
    Electronic Resource
    Electronic Resource
    3-methoxytyramine: Its suitability as an indicator of synaptic dopamine release (1981)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 315 (1981), S. 219-225 
    Details
    ISSN: 1432-1912
    Keywords: 3-Methoxytyramine ; Haloperidol ; Dopamine release ; Dopamine agonists ; Gas chromatography ; Mass Spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The value of 3-methoxytyramine (3-MT) as an indicator of impulse-related dopamine (DA) release has been assessed in rat corpus striatum. Moreover, the turnover of 3-MT was estimated by measuring its disappearance rate after COMT inhibition. Quantitation of 3-MT and DA was performed by gas chromatography/mass spectrometry (selected ion monitoring). Haloperidol in doses between 0.05 and 3 mg/kg p.o. did not increase endogenous 3-MT levels at any time up to 24 h after its administration, whereas it dose-dependently increased homovanillic acid and 3,4-dihydroxyphenylacetic acid. However, in doses above 0.1 mg/kg p.o., it enhanced the accumulation of 3-MT in clorgyline-pretreated animals. Conversely, baclofen in doses of 2 mg/kg i.p. and above decreased endogeneous 3-MT levels, but reduced the accumulation of this amine only poorly at 20 mg/kg i.p. in clorgyline-pretreated rats. A number of dopamine agonists, apomorphine (0.5 mg/kg i.v.), dipropyl-ADTN (0.03 mg/kg i.v.), but not bromocriptine (1 mg/kg i.v.) reduced endogenous 3-MT levels 10 min after administration by approximately 50%. The DA releasing agents d-amphetamine and methylphenidate showed different effects: the former increased endogenous 3-MT greatly, whereas the latter was without effect. The difference is likely to be related to the MAO inhibitory properties of amphetamine. 3-MT disappeared rapidly after COMT inhibition with 50 mg/kg i.v. tropolone (half-life of the initial disappearance about 1 min). The curve flattened off after 5–10 min. Turnover was calculated to be about 7 nmol/g/h, which corresponds to about a third of the turnover of DA. Our results suggest that an important part of DA metabolism occurs through 3-MT and that this amine is very effectively deaminated by MAO-A, so effectively indeed that increased formation does not increase its endogeneous levels. It appears, therefore, that 3-MT is not suitable as an indicator of increased DA release. However, it seems to have some value for an assessment of lowered DA release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00499838
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  • 4
    Electronic Resource
    Electronic Resource
    Total cross section for hadron production bye + e − annihilation between 9.4 and 9.5 GeV (1980)
    Springer
    The European physical journal 6 (1980), S. 125-129 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The total cross section fore + e − annihilation into hadrons for center of mass energies from 9.4 to 9.5 GeV has been measured with the nonmagnetic DESY-Heidelberg detector at DORIS. A value ofR=σhad/σµµ=3.8±0.7 for the continuum region around the Υ (9.46) resonance has been determined. The ratioΓ ee Γ had/Γ tot of electronic, hadronic and total widths has been reevaluated to be (1.00±0.23) keV for the Υ resonance and (0.37±0.16) keV for the Υ′. In addition, a search for directly produced pohotons from Υ decays of the type Υ→γ+gluon+gluon has been performed. The Υ decay into muon pairs has also been searched for.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01588838
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  • 5
    Electronic Resource
    Electronic Resource
    Interpretation of the stress dependence of the steady state creep rate of Zirkaloy 4 at 873 K in terms of the knitting model (1985)
    Springer
    Czechoslovak journal of physics 35 (1985), S. 302-306 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The creep rate of Zircaloy 4 has been determined as a function of strain at constant stressσ in the range 50 〈σ/MPa 〈 124. The steady state dislocation structure is a subgrain structure. The average subgrain size varies with stress as9·9G b/σ (G: shear modulus,b: Burgers vector). Stress reduction tests have been performed during steady state creep to determine the static elastic modulus, the anelastic back flow and the transient creep curve caused by the stress reductions. The results are analysed in terms of the knitting model of creep. It is shown that the stress dependence of the steady state creep rate can be described by the model provided that a particle hardening term is taken into account.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01605100
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  • 6
    Electronic Resource
    Electronic Resource
    Application of low energy CID in the determination of structures of [M - halogen]+ ions obtained from diethyl halosuccinates under electron impact (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1987), S. 61-63 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Low energy collision induced dissociation (CID) spectra indicate that m/z 173 ions formed by the loss of a halogen atom from diethyl chloro- and bromo-succinate under electron impact are mixtures of O-protonated diethyl maleate (〉90%) and fumarate (〈10 %). Hydrogen migration precedes the C-halogen bond cleavage in these cases. The low energy CID spectrum of the m/z 173 [M—I]+ ion obtained from diethyl iodosuccinate shows that only a small fraction of the [M—I]+ ions are the O-protonated species formed by hydrogen migration. The results of this study demonstrate the potential of low energy CID in the determination of structure (including configuration) of gas phase ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210220202
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  • 7
    Electronic Resource
    Electronic Resource
    Configurational assignment of fragment ions by CID. Stereochemistry and mechanism of retro-Diels-Alder fragmentation accompanied by hydrogen transfer in gas-phase cations (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1987), S. 3-5 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Low energy CID mass spectra of m/z 173, C8H13O4+, obtained from the diethyl ester of cis,syn,cis-l,2,3,3a,4,5,5a,6,7,8-decahydroindacene-4,5-dicarboxylic acid and cis,syn,cis-l,2,3,4,5,6,7,8,8a,9,10,10a-dodecahydrophenanthrene-9,10-dicarboxylic acid indicate they have the structure of protonated diethyl maleate. This finding together with previous deuterium labelling results suggest that the formation of this ion from both precursors takes place by migration of a hydrogen atom from an allylic δ-position followed by the concerted cleavage of two allylic C—C bonds in analogy to the ground state retro-Diels-Alder fragmentation.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210220103
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  • 8
    Electronic Resource
    Electronic Resource
    Direct stereochemical assignment of sugar subunits in naturally occurring glycosides by low energy collision induced dissociation. Application to papulacandin antibiotics (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 441-446 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A tandem mass spectrometric method is described which allows the assignment of stereochemistry to fragment ions comprising intact sugar subunits of larger glycosides without chemical degradation and product isolation by chromatography. The approach relies on the mass selection of the ‘sugar ion’ of interest followed by analysis of stereoselective fragmentation induced by low-energy collisional activation. The daughter ion spectra provide configurational fingerprints of the selected sugar ions which can be matched for identity with reference spectra obtained from suitable precursors of known stereochemistry. Glucose, mannose and galactose furnished the required set of the most important reference ions. By using peracetyl (and perdeuterioacetyl) derivatives, galactose was readily identified as the glycosidic sugar constituent of the (known) antibiotic papulacandin B and a further (unknown) congener.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200150805
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation of inert and high-temperature stable apolar and medium polar glass-capillary columns using OH-terminated polysiloxane stationary phases (1985)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 718-726 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary columns, glass ; Inert, stable stationary phases ; Leaching ; Immobilization by condensation ; OH terminal groups ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Coating intensively leached silica surfaces with OH-terminated phases provides a new way of producing, by simple means, columns with substantially increased inertness and thermostability. In addition, their separation efficiency is found to be typically higher than that of columns with traditional coatings. The underlying basic effect is a condensation process between terminal silanol groups of the phase and residual silanols, of the glass surface, thus producing the mentioned inertness. Moreover, the surface-bonded molecules are immobilized without addition of a radical generator. If required, crosslinking can also be effected using a volatile azo compound. No vinyl groups are required for this additional immobilization process. The paper discusses all processes involved, and gives detailed working directions for the following medium polar phases. OV-1701-OH, OV-31-OH (new, 17% cyanopropyl), OV-61-OH, and OV-17-OH, and the apolar phases PS-347.5 and PS-086. There is no doubt so far that the principle of terminal silanol groups is applicable to all silicone phases, and may replace the traditional endcapped stationary phases in the future.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240081106
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  • 10
    Electronic Resource
    Electronic Resource
    Preparation of inert glass capillary columns coated with UCON 50 HB-5100. An attempt to rediscover industrially produced α, ω-polyethylene/polypropyleneglycol ethers as stationary phases in capillary gas chromatography (1987)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 32-38 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary columns, glass ; Polyalkyleneglycol ether phases ; Inert columns ; Immobilization by condensation ; Methyltrimethoxysilane, coupling agent ; Trifluoroacetic acid, catalyst ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using UCON 50 HB-5100, one of the most successful stationary phases in capillary gas chromatography during the past decade, as an example, we wish to redirect attention to the excellent properties of the polyethylene/polypropyleneglycol ether copolymer coatings. Based on experience gained in work with OH-terminated polysiloxanes, a method is described for preparing inert and relatively temperature stable chemically bonded and crosslinked coatings in a single working step. Methyltrimethoxysilane was used as coupling agent, and trifluoroacetic acid was introduced as an acidic catalyst. The reaction mechanisms involved as well as the influence of additional crosslinking on the column behavior are discussed, particularly with respect of the inertness of the coatings.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240100107
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