bluuebunny/crossref_metadata_2025_split huggingface dataset:
Erhöhung der Nachweisempfindlichkeit von Cyclosporin A durch Derivatisierung mit 2‐Naphthylselenylchlorid
Authors: Gfeller Jean‐Claude , Beck Albert K. , Seebach Dieter 
Published: December 2004

Enhancement of Detection Sensitivity of Cyclosporin A by Derivatization with 2‐NapthylselenylchlorideThe UV./HPLC. detection sensitivity of cyclosporine A 1, an immunosuppressive cyclic undecapeptide containing one D‐aminoacid and seven N‐methylated aminoacids, is enhanced by a factor of 3‐4 (limit of detection 5 ng) by conversion of the characteristic side chain of amino‐acid‐1 to the β‐naphthylseleno‐substituted tetrahydrofuran derivative 4.
(Butadiene)tricarbonylosmium synthesis and structural comparison with the Fe‐ and Ru‐complexes based on 1H‐ and 13C‐NMR. Spectroscopy
Authors: Zobl‐Ruh Susanne , Von Philipsborn Wolfgang 
Published: December 2004

AbstractThe photochemical synthesis of the title complex from 1,3‐butadiene and dodecacarbonyltriosmium is described. The 1H‐NMR. and H‐coupled 13C‐NMR. spectra are analyzed completely and the H, H‐ and C,H‐coupling constants compared with the data of the corresponding Fe‐ and Ru‐complexes. One‐bond 13C, 13C‐coupling constants are reported for a series of complexed 1,3‐dienes. All data are consistent with an increasing distortion from planarity of the C,H‐skeleton at the terminal diene C‐atoms in the sequence Fe → Ru → Os.
Die Synthese von 6exo‐substituierten p‐Toluolsulfonsäure‐[2endo‐norbornyl]estern. Norbornanreihe, 2. Mitteilung
Authors: Fischer Walter , Grob Cyril A. , Von Sprecher Georg , Waldner Adrian 
Published: December 2004

The synthesis of 6exo‐Substituted 2endo‐Norbornyl p‐ToluenesulfonatesThe preparation of hitherto unknown p‐toluenesulfonates of 6exo‐substituted 2endo‐norbornanols is described.
The Rates of Diazomethane Formation from Methylnitrosoamides. The stability of diazomethane solutions towards aqueous alkalis
Authors: Pearce Michael 
Published: December 2004

AbstractThe rate of hydrolysis of N‐methyl‐N‐nitrosoamides by aqueous alkalis varies greatly. Methylnitrosourea (1) is hydrolyzed rapidly by aqueous KOH‐solutions at low temperatures to give a high yield of diazomethane. Under similar conditions, N,N′‐dimethyl‐N,N′‐dinitroso‐oxamide (3) is hydrolyzed more slowly, but also gives a good yield of diazomethane. N,N′‐Dimethyl‐N,N′‐dinitrosoterephthal‐amide (4), and (N‐methyl‐N‐nitroso)‐4‐amino‐4‐methyl‐2‐pentanone (5) are less easily hydrolyzed by aqueous KOH‐solutions. N‐Methyl‐N‐nitroso‐p‐toluenesulfonamide (2) was the least reactive out of those tested. The hydrolysis of diazomethane in toluene with aqueous bases follows first order kinetics. The hydrolysis rate is greatly influenced by the concentration and strength of the base and temperature.
Über die Temperaturabhängigkeit der 13C‐NMR.‐Spektren von Tetracarbonyl (η‐(Z)‐cycloocten)eisen und (Z)‐cycloocten
Authors: Von Büren Martin , Cosandey Marcel , Hansen Hans‐Jürgen 
Published: December 2004

On the Temperature Dependence of the 13C‐NMR.‐Spectra of Tetracarbonyl (η‐(Z)‐cyclooctene)iron and of (Z)‐CycloocteneReaction of (Z)‐cyclooctene (1) with Fe2(CO)9 in pentane at 0° yielded tetracarbonyl(η‐(Z)‐cyclooctene)iron (2) as a yellow oil which can be stored over a longer period only at −78°.It is shown that the title compounds (1 and 2, respectively) are fluxional.The activation parameters for the conformational C‐atom site exchange of (Z)‐cyclooctene (1) and tetracarbonyl (η‐(Z)‐cyclooctene)iron (2) (in CCl2F2) have been determined between 113 K and 151 K for 1 and between 151 K and 205 K for 2, respectively, by a complete line shape analysis of the temperature dependent proton noise‐decoupled 13C‐NMR. signals of the olefinic C‐atom. The kinetic data and activation parameters are given in Tables 1 and 2.
The Synthesis of Cystine Peptides by Iodine Oxidation of S‐Trityl‐cysteine and S‐Acetamidomethyl‐cysteine Peptides
Authors: Kamber Bruno , Hartmann Albert , Eisler Karel , Riniker Bernhard , Rink Hans , Sieber Peter , Rittel Werner 
Published: December 2004

AbstractPreviously reported studies of the iodine oxidation of S‐trityl‐cysteine peptides and S‐acetamidomethyl‐cysteine peptides, leading directly to cystine peptides, have been extended. Detailed investigations have been made of the reactivities of the S‐trityl and the S‐acetamidomethyl group towards iodine in various solvents. In chloroform, methylene chloride, trifluoroethanol, and hexafluoroisopropyl alcohol the differences in the reaction rates of the two groups have been found to be extremely large, allowing the selective conversion of the tritylthio groups to disulfides in the presence of the S‐acetamidomethyl derivatives. In a second group of solvents, consisting of methanol, acetic acid, dioxane, and mixtures of these solvents with water, simultaneous iodine oxidation of S‐trityl‐ and S‐acetamidomethyl‐cysteine peptides leads to a preferential combination of these two residues, resulting in predominantly asymmetrical cystine derivatives. ‐ The suitability of the two sulfur‐protecting groups in the synthesis of cyclic cystine peptides has been assessed. ‐ Possible reaction mechanisms are discussed. ‐ The scope and limitations of iodine oxidation in peptide synthesis have been studied.The applicability of the method has been demonstrated in the preparation of the open‐chain asymmetrical cystine peptide 5, the protected somatostatin derivative 17, and the A(1–13) segment 19 of human insulin, previously employed in the total synthesis of this hormone.
Die Hydrolyse von 6exo‐substituierten 2exo‐ und 2endo‐Norbornylestern der p‐Toluolsulfonsäure. Norbornanreihe. 3. Mitteilung
Authors: Fischer Walter , Grob Cyril A. , Von Sprecher Georg , Waldner Adrian 
Published: December 2004

The Hydrolysis of 6exo‐Substituted 2exo‐ and 2endo‐Norbornyl p‐Toluenesulfonates. Norbornane Series. Part 3Hydrolysis of the 6exo‐substituted 2exo‐ and 2endo‐norbornyl p‐toluenesulfonates 1b‐1 and 2b‐1, respectively, in 70% dioxane led to different amounts of the following products: Unrearranged 2exo‐norbornanols 3 and norbornenes 5, accompanied in somes cases by small amounts of the rearranged Rendo‐epimers 4 and 6 and by norticyclenes 7. When the 6exo‐substituent was a nucleophilic group as in 1e‐1 and 2e‐1, various amounts of tricyclic products were also formed by endo‐cyclization. These results show that the 2exo‐ and 2endo‐esters 1 and 2, respectively, react by way of different intermediates. In cases where the 6exo‐substituent was an n‐electron donor, as in 1m‐r and 2m‐r, quantitative fragmentation to (3‐cyclopentenyl)acetaldehyde (13) occurred.
The Homoallyl‐Cyclopropylcarbinyl Cation Rearrangement in the Solvolyses of exo‐ and endo‐5‐Norbornen‐2‐yl p‐Bromobenzenesulfonates. Application of 2H‐NMR. Spectroscopy
Authors: Burger Ulrich , Sonney Jean‐Marie , Vogel Pierre 
Published: December 2004

AbstractThe buffered trifluoroethanolyses and acetolyses of exo‐(2‐D)‐ (6) and endo‐(2‐D)‐5‐norbornen‐2‐yl brosylates (7) yielded exo‐5‐norbornen‐2‐yl and 3‐nortricyclyl derivatives. The deuterium distribution in these products was determined unambiguously by 2H‐NMR. and MS. In contrast to previous reports, each hydrogen and, consequently, each deuterium atom could be identified. Product ratio and label distribution in the solvolysis of 6 make unnecessary the intervention of asymmetrical homoallylic cation intermediates. The results are most economically rationalized by invoking symmetrical 3‐nortricyclyl ion‐pair intermediates.
Optical activity in remotely perturbed exocyclic s‐cis‐butadienes. Preparation and circular dichroism of enantiomerically pure 5,6‐dimethylidene‐2‐norbornyl derivatives
Authors: Sonney Jean‐Marie , Vogel Pierre 
Published: December 2004

AbstractOptically pure 5, 6‐dimethylidene‐exo‐2‐norbornanol ((+)‐1), acetate ((+)‐2), p‐bromobenzenesulfonate ((+)‐3), 5, 6‐dimethylidene‐endo‐2‐norbornanol ((+)‐4), acetate ((+)‐5), p‐bromobenzenesulfonate ((+)‐6) and 5, 6‐dimethylidene‐2‐norbornanone ((+)‐7) have been prepared. Their chirality was correlated chemically with that proposed by Mislow et al. for (+)‐benzo‐5‐norbornen‐2‐yl acetate ((+)‐14). The solution CD. spectra of these remotely perturbed exocyclic s‐cis‐butadienes are reported and discussed briefly. Unexpectedly, the β,γ‐unsaturated ketone (+)‐7, for which transannular interaction between the ketone and diene functions was revealed by its UV. absorption spectrum, showed (in isooctane) two weak Cotton effects of opposite sign between 265 and 340 nm.
Classification of the CD. Spectra of carotenoids
Authors: Sturzenegger Verena , Buchecker Richard , Wagnière Georges 
Published: December 2004

AbstractThe CD. spectra of carotenoids in the 220‐500 nm region may by inspection be classified as (a) essentially Conservative, (b) intermediate, or (c) essentially nonconservative. A conservative spectrum shows in that spectral region a sequence of 5‐6 relatively sharp Cotton effects of alternating sign, the rotatory strengths of which roughly add to zero. In a non‐conservative spectrum Δϵ has the same sign over the whole region and its absolute value is in general somewhat smaller. In general, typical conservative spectra invert upon isomerization of the molecule from all‐trans to mono‐cis. Non‐conservative spectra do not invert. The model of a chiral polyene of the length of the conjugated carotene chromophore reproduces well the main features of the conservative spectra. The theoretical predictions and the experimental data are shown to conform to the C2‐rule [43] [44]. The particular nature of the longest‐wavelength transition is interpreted. Based on a summary of the chiroptic data on about 50 naturally occurring compounds, the question is discussed of when conservative spectra arise and when not.
An Efficient Synthesis of 2,3,5,6‐Tetramethylidene‐7‐oxanorbornane
Authors: Mahaim Cyril , Carrupt Pierre‐Alain , Hagenbuch Jean‐Pierre , Florey André , Vogel Pierre 
Published: December 2004

AbstractPalladium‐catalyzed double carbomethoxylation of the Diels‐Alder adduct of furan and maleic anhydride yielded the methyl all‐exo‐7‐oxanorbornane‐2,3,5,6‐tetracarboxylate (7) which was transformed in three steps into 2,3,5,6‐tetramethylidene‐7‐oxanorbornane (1), a useful synthon. Six isomeric methyl 7‐oxanor‐bornane‐2,3,5,6‐tetracarboxylates (7–12) have been isolated and their 1H‐ and 13C‐NMR. data are compared.
«3‐Fluorisopren» (2‐Fluor‐3‐methyl‐1,3‐butadien) und einige heterosubstituierte Abkömmlinge
Authors: Schlosser Manfred , Spahie Bojana 
Published: December 2004

‘3‐Fluoroisoprene’ (2‐Fluoro‐3‐methyl‐1,3‐butadiene) and Some Hetero‐substituted Derivatives ThereofThe readily accessible 1‐chloro‐1‐fluoro‐2‐iodomethyl‐2‐methylcyclopropane undergoes zinc‐promoted ring‐cleavage yielding 2‐fluoro‐3‐methyl‐1, 3‐butadiene (‘3‐fluoroisoprene’) in almost quantitative yield. Alternatively the iodine atom may be replaced by electron‐attracting groups such as cyano, benzenesulfonyl or triphenylphosphonio. Ring‐opening of the resulting derivatives can then be brought about by various bases and leads to substituted fluorodienes. ‐ The chemical reactivity of ‘3‐fluoroisoprene’ has been studied in some detail. For example, it was found to add bromine at temperatures below 0° under kinetic control and to afford mainly the 1,4‐adduct having the (Z)‐configuration besides smaller quantities of the 1,2‐ and 3,4‐adduct. At room temperature this mixture slowly undergoes a transformation yielding, as the sole products, both stereoisomeric 1, 4‐adducts in a 1:1 ratio.
Die Stereochemie der fragmentierenden Enthalogenierung von 1‐Chlor‐1‐fluor‐2‐(1‐halogenalkyl)cyclopropanen
Authors: Spahić Bojana , Schlosser Manfred 
Published: December 2004

The Stereochemistry of the Fragmentative Dehalogenation of 1‐Chloro‐1‐fluoro‐2‐(1‐halogenalkyl)cyclopropanesA number of model substrates were submitted to zinc‐promoted fragmentation, and the composition of the resulting mixture of isomeric fluorodienes was determined. The exocyclic reaction center, bearing the electrofugal leaving group, was found to undergo almost complete stereochemical randomization in the course of the reaction. On the other hand, the ring‐opening proceeds stereoselectively. The rotation, which brings the substitutents of the halogen‐free ring position into the plane of the new, fluorine‐bearing double‐bond, occurs mainly in that sense to move the electrons of the breaking ring linkage into the rear of the departing chlorine atom.
Halochrome Molekeln 3. Mitteilung [1]. Thermodynamische und kinetische Untersuchungen zum acidobasischen Verhalten substituierter 6,6‐Diphenyl‐6H‐chromeno[4,3‐b]indole
Authors: Hellrung Bruno , Balli Heinz 
Published: December 2004

Halochromic Molecules. Thermodynamics and Kinetics of the Acidobasic Behaviour of Substituted 6,6‐Diphenyl‐6H‐Chromeno [4,3‐b]IndolesThe complex halochromic behaviour of substituted 6, 6‐Diphenyl‐6 H‐chromeno‐[4,3‐b]indoles was investigated by stopped flow techniques and spectrometric methods in 64% methanol/water mixtures at 25°. pK‐values are determined, rates and mechanisms of coloration reaction are investigated and results are discussed.
Crystal and Molecular Structure of (±)‐8,8‐Dimethyl‐6,7‐diazabicyclo[3.3.0]octa‐1,6‐diene 7‐oxide
Authors: Maverick Andrew W. , Maverick Emily F. , Olsen Henrik 
Published: December 2004

AbstractThe exclusive product of thermal rearrangement of (±)‐7‐isopropylidene‐2,3‐diazabicyclo[2.2.1]hept‐2‐ene N‐oxide (2) has been identified as the title compound (1). The compound crystallizes in the orthorhombic space group Pbca (No. 61), with a= 8.953 (2), b= 12.740 (2), c=14.446 (3) Å; Z= 8; px=1.227 g cm−3. The details of the molecular structure are not unusual, except for a long C–N distance (C(8)–N(7), 1.560 (4) Å). No significant short intermolecular contacts are observed in the crystal.
Synthèse partielle et propriétés oncostatiques des pseudo‐tubulosines, analogues de l'émétine et de la tubulosine
Authors: Seguin Elisabeth , Koch Michel , Chenu Evelyne , Hayat Marcel 
Published: December 2004

Partial Synthesis and Oncostatic Properties of Pseudotubulosines, Analogues of Emetine and TubulosinePseudotubulosines, structural analogues of emetine and tubulosine, have been synthesized by either Pictet‐Spengler or Bischler‐Napieralski condensation from dihydrocorynantheal or corynantheidal. Spectral data, cytotoxic and oncostatic properties of these new alkaloids are described.
Glutamate and prostaglandin E2in the trapezius muscle of female subjects with chronic muscle pain and controls determined by microdialysis
Authors: Flodgren Gerd M. , Crenshaw Albert G. , Alfredson Häkan , Fahlström Martin , Hellström Fredrik B. , Bronemo Lars , Djupsjöbacka Mats 
Published: December 2004

AbstractMuch is still unknown concerning the mechanisms underlying the development of chronic muscle pain. The presence and magnitude of inflammatory substances and neurotransmitters in chronic painful conditions is not clear. The aims of the present study were to determine, with the use of microdialysis, the interstitial concentrations and the equilibration times for PGE2and glutamate in the trapezius muscles of nine female subjects with chronic muscle pain, and nine pain‐free age‐matched controls. A microdialysis probe was implanted in the upper part of the trapezius muscle and perfused with Ringer‐acetate solution at a flow rate of 0.3 μL/min. Samples were obtained every 30 min, during a 4‐h rest period. At equilibration, the mean concentrations (−SE) of PGE2were 0.71 (−0.11) ng/mL for the pain‐group and 0.97 (−0.35) ng/mL for the controls. For glutamate the mean concentrations for the pain‐group were 66.3 (−13.3) μmol/L and 60.6 (−22.9) μmol/L for the controls. For the pain group and the control group, respectively, equilibration for PGE2was reached at 180 and 150 min, and for glutamate at 150 and 120 min. The present study showed no differences between groups in the concentrations of PGE2and glutamate in the trapezius muscle. Further, it revealed that when using the slow‐flow method, a period of at least 2.0‐2.5 h is needed, after probe insertion, to reach steady state for glutamate and PGE2.
Central pain in multiple sclerosis — prevalence and clinical characteristics
Authors: Österberg A. , Boivie J. , Thuomas K.‐Å. 
Published: December 2004

AbstractPain is more common in multiple sclerosis (MS) than has previously been recognised. In the present study we have investigated the occurrence of central pain (CP) in MS and defined its characteristics. Questionnaires were sent to all 429 patients with definite MS in the patient register at our neurology department. All admitting to pain were interviewed and offered an extended interview and examination. Three hundred and sixty four patients responded (86%), of whom 57.5% reported pain during the course of their disease (21% nociceptive, 2% peripheral neuropathic and 1% related to spasticity). One hundred patients (27.5%) had CP, including 18 patients (4.9%) with trigeminal neuralgia.The non‐trigeminal CP was, in 87%, located in the lower and in 31% in the upper extremities. It was mostly bilateral (76%) and constant, with 88% experiencing daily pain. Only 2% had paroxysmal attacks. Aching, burning, pricking were the commonest qualities. The pain was intense with small to moderate spontaneous variation. In 5.5% of all patients (20% of the patients with CP), pain was a presenting symptom, alone or in combination with other symptoms.The most common neurological symptoms/signs besides CP were sensory abnormalities (98%, dominated by abnormal sensibility to painful stimulus and temperature). Trigeminal neuralgia in MS started later in life and after longer disease duration than non‐trigeminal pain. Both types of CP existed either chronically or as a feature of relapse. Central pain is thus an important symptom in MS (around 30%) and causes much suffering.
Innocuous skin cooling modulates perception and neurophysiological correlates of brief CO2 laser stimuli in humans
Authors: Nahra Hicham , Plaghki Léon 
Published: December 2004

AbstractThe present study examined the influence of innocuous skin cooling on the perception and neurophysiological correlates of brief noxious CO2 laser stimuli. In nine normal subjects, brief CO2 laser pulses of four different intensities (duration 50 ms; diameter 5 mm; intensity range 5.8–10.6 mJ/mm2) were delivered at random every 5–10 s on the dorsum of the hand. Innocuous skin cooling was performed by a thermode (20 °C; 3 × 3 cm) with a central hole for the laser test stimuli. Quality and intensity (VAS) of perceptions, reaction times and laser evoked potentials (LEPs) were examined. Signal detection theory analysis was performed to evaluate discrimination performance and decision criterion. During innocuous skin cooling, detection threshold increased from 4.8 − 1.81 to 8.2 − 1.05 mJ/mm2 and pain threshold from 8.7 − 1.53 to 13.5 − 1.57 mJ/mm2. proportion of detected stimuli decreased from 87% to 48% and pain reports from 42% to 10%. The well localized ‘pricking’ sensation mediated by Aδ‐nociceptors almost vanished. The intensity of sensations (VAS scores) was considerably reduced. Sensory discriminative performance was significantly depressed but decision criterion remained unchanged. Reaction times were delayed. The late‐LEPs, correlates of Aδ‐nociceptor activations, were also significantly depressed while the ultra‐late LEPs, correlates of C‐nociceptors, were not affected.Taken together, these results strongly suggest that innocuous skin cooling interfered with the sensory processing of laser heat stimuli and more prominently with those related to Aδ‐nociceptive input.
How do multiple environmental cycles in combination determine reproductive timing in marine organisms? A model and test
Authors: Yamahira K. 
Published: December 2004

Summary

Each of the multiple environmental cycles – the light–dark, tidal, semilunar, lunar and seasonal cycles – may have an independent, specific effect on reproductive timings of marine organisms and can alone or in combination produce a variety of temporal reproductive patterns. Assuming that each ecological interaction with these fluctuating environmental cycles generates a unique functional relationship between a component of fitness and the timing of reproduction, a model is proposed that predicts that all fitness components are multiplicative and therefore the reproductive timing is entrained or driven by a cycle(s) having a sharp functional curve of the relevant fitness component.
According to this model, many of the reproductive patterns, ranging from diel to lunar, commonly seen in marine organisms were explained by changing relative kurtosis among functional curves of fitness components. Each curve could also differ in its optimum and skewness, making various intermediates and modifications possible.
As a model system for the model to be applied, intraspecific variation in the timing of spawning by a puffer, Takifugu niphobles (Jordan & Snyder) was examined. The patterns of daily variation in a day's spawning time within a population and geographical variation in spawning days among populations indicated that (1) the semilunar cycle (i.e. spring–neap tide cycle) has no direct influence on spawning days, (2) a combination between the functional curves of the fitness components associated with the light–dark and tidal cycles produce an apparent biweekly, semilunar spawning rhythm, (3) the curves may be skewed toward earlier and later times, respectively, and (4) their form may differ among populations.
This model approach argues that to understand the ecology and evolution of temporal patterns of reproduction, one must properly decouple and evaluate the form of the functional curve of a fitness component associated with each of the multiple environmental cycles.
Arsenic trioxide is effective in the treatment of multiple myeloma in SCID mice
Authors: Rousselot Philippe , Larghero Jérôme , Labaume Sylvaine , Poupon Joël , Chopin Martine , Dosquet Christine , Marolleau Jean‐Pierre , Janin Anne , Brouet Jean‐Claude , Fermand Jean‐Paul 
Published: December 2004

Abstract:Objectives : Pharmacological concentrations of arsenic trioxide (ATO) and organic arsenic melarsoprol induce apoptosis in malignant plasma cells. In an attempt to further document the interest of the arsenic in vivo, we treated severe combined immunodeficient (SCID) mice transplanted with human myeloma cells by ATO or melarsoprol.Methods : Fifty‐two SCID mice were irradiated before intraperitoneal (i.p.) injection of plasma cells from five myeloma patients. Engraftment was assessed by serial measurement of the human monoclonal immunoglobulin G (HuMIgG) concentration in mouse serum. Treatment with ATO (10 μg/g i.p. 5 d a week), melarsoprol (30 μg/g i.p. 5 d a week) or phosphate buffer saline was started when a sustained growth of the tumor cells was demonstrated.Results : Seventeen mice developed the human tumor. A significant decrease in HuMIgG amounts was observed in three of five mice of the ATO group, including two that achieved an apparent complete remission persisting up to 5 months after ATO discontinuation. In these mice, no human plasma cells were detected in tissue samples collected postmortem. Soluble human interleukin‐6 receptor amount, measured in mice sera as a surrogate marker of the plasma cell proliferation, varied in parallel with HuMIgG concentration. A significant difference in survival was observed between control and ATO treated mice (113 and 158 d, respectively; P = 0.01) whereas no difference could be evidenced in control and melarsoprol groups.Conclusion : Present study confirms in vivo the in vitro effects of ATO on myeloma cells. Delayed relapses were observed suggesting that prolonged or maintenance therapy has to be considered in future clinical trials. Whether or not this will translate into clinically relevant effect of the drug in myeloma patients deserves further consideration.