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  • 1995-1999  (3,577)
  • 1997  (3,577)
  • Biochemistry and Biotechnology  (1,317)
  • Organic Chemistry  (824)
  • Engineering  (683)
  • Inorganic Chemistry  (608)
  • Human  (145)
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  • 1995-1999  (3,577)
Year
Keywords
  • 101
    Electronic Resource
    Electronic Resource
    Kinesthetic perceptions of intrinsic anterior-posterior axes (1997)
    Springer
    Experimental brain research 117 (1997), S. 465-471 
    Details
    ISSN: 1432-1106
    Keywords: Key words Coordinate system ; Upper limb ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The purpose of this research was to investigate whether kinesthetic and proprioceptive perceptions of “straight ahead” were defined by a head- or trunk-fixed axis. Subjects were instructed to align the forearm with the head or trunk anterior-posterior (a/p) axis by elbow flexion or extension in the horizontal plane in five different conditions. In each condition the experimenter varied initial elbow and shoulder horizontal flexion or extension angles and head and/or trunk orientation (by rotation about a vertical axis) on each trial before the subject moved the forearm to align it with the head or trunk axis. The upper limb motion was voluntarily constrained to the horizontal plane through the shoulder. Variable errors were significantly lower when subjects aligned the forearm to the trunk-fixed a/p axis. Furthermore, the perceptual errors showed a greater dependence on body segment orientations when the forearm was aligned to the head axis than to the trunk axis. We conclude that the trunk a/p axis is preferred to the head a/p axis for specifying upper limb segment orientations in the horizontal plane at the kinesthetic perceptual level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050242
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  • 102
    Electronic Resource
    Electronic Resource
    Effect of contraction strength on responses in biceps brachii and adductor pollicis to transcranial magnetic stimulation (1997)
    Springer
    Experimental brain research 117 (1997), S. 472-478 
    Details
    ISSN: 1432-1106
    Keywords: Key words Transcranial magnetic stimulation ; Motor cortex ; Motor-evoked potentials ; Silent period ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The sizes of the motor-evoked potentials (MEPs) and the durations of the silent periods after transcranial magnetic stimulation were examined in biceps brachii, brachioradialis and adductor pollicis in human subjects. Stimuli of a wide range of intensities were given during voluntary contractions producing 0–75% of maximal force (maximal voluntary contraction, MVC). In adductor pollicis, MEPs increased in size with stimulus intensity and with weak voluntary contractions (5% MVC), but did not grow larger with stronger contractions. In the elbow flexors, MEPs grew little with stimulus intensity, but increased in size with contractions of up to 50% of maximal. In contrast, the duration of the silent period showed similar changes in the three muscles. In each muscle it increased with stimulus intensity but was unaffected by changes in contraction strength. Comparison of the responses evoked in biceps brachii by focal stimulation over the contralateral motor cortex with those evoked by stimulation with a round magnetic coil over the vertex suggests an excitatory contribution from the ipsilateral cortex during strong voluntary contractions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050243
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  • 103
    Electronic Resource
    Electronic Resource
    Human herpes virus 6 and human herpes virus 8 DNA sequences in brains of multiple sclerosis patients, normal adults and children (1997)
    Springer
    Journal of neurology 244 (1997), S. 450-454 
    Details
    ISSN: 1432-1459
    Keywords: Key words Multiple sclerosis ; Human herpesvirus 6 ; Human ; herpesvirus 8 ; Polymerase chain ; reaction ; Brain DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to determine whether the newly discovered human herpesviruses (HHVs) are involved in multiple sclerosis (MS), we investigated by polymerase chain reaction the presence of specific deoxyribonucleic acid (DNA) sequences belonging to human herpesvirus 6 (HHV-6) and to human herpesvirus 8 (HHV-8), in the peripheral blood mononuclear cells (PBMCs), and in the brain and spinal cord plaques from MS patients. Normal adult and stillborn children’s brains were investigated as controls. PBMCs from 56 MS patients contained HHV-6 DNA in only 3 cases and in none were there HHV-8 sequences. The cerebral DNA from 5 MS patients was positive for HHV-8 and not for HHV-6 sequences, while the nervous tissue of one patient who died with neuromyelitis optica was positive for HHV-6 and negative for HHV-8. The brains of 4/8 adult controls were positive for HHV-6, as were 3/8 for HHV-8; none of the 7 stillborn children’s cerebral tissue contained HHV-6 sequences, while 2 contained HHV-8 DNA. Although these data do not support a hypothesis that there is a role for these two HHVs in the pathogenesis of MS, nevertheless it may be suggested that (1) the two viruses possess strong neurotropism and the central nervous system seems to be a reservoir for them (2) HHV-6 infection is probably not transmitted maternally, but is acquired later in infancy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050121
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  • 104
    Electronic Resource
    Electronic Resource
    Multifocal motor neuropathy (1997)
    Springer
    Journal of neurology 244 (1997), S. 143-152 
    Details
    ISSN: 1432-1459
    Keywords: Key words Multifocal motor ; neuropathy ; Conduction block ; Anti-GM1 antibodies ; Cyclophosphamide ; Human ; immunoglobulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present a review of the literature on multifocal motor neuropathy (MMN), a rare neurological disorder which has features in common with both chronic inflammatory demyelinating neuropathy and lower motor neuron disease. Clinically, MMN is characterised by slowly progressive asymmetrical limb weakness, usually most prominent in the forearms. Weakness may be associated with muscle wasting, fasciculations and decreased tendon reflexes. Serum anti-GM1 ganglioside antibody titres may be increased. The diagnostic hallmark of MMN is the electrophysiological demonstration of persistent localised motor conduction blocks, with otherwise normal or near-normal motor and sensory conduction velocities. The pathogenesis of MMN has not been elucidated completely. There is, however, substantial evidence for an autoimmune mechanism. Based on the possible involvement of the immune system in the pathogenesis of MMN the therapeutic efficacy of several immunomodulatory drugs has been tested. Treatment of MMN patients with human immunoglobulin or cyclophosphamide is usually followed by a marked improvement of strength. The finding that MMN is a potentially treatable disorder underscores the importance of distinguishing MMN from lower motor neuron disease, for which no effective therapy is currently available.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050065
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  • 105
    Electronic Resource
    Electronic Resource
    Binge cocaine self-administration in humans: intravenous cocaine (1997)
    Springer
    Psychopharmacology 132 (1997), S. 375-381 
    Details
    ISSN: 1432-2072
    Keywords: Key words Cocaine ; Human ; Intravenous ; Self-administration ; Binge ; Cardiovascular effects ; Subjective effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cocaine is frequently used in intermittent cycles of repeated dosing, or “binges.” This pattern of cocaine use has been difficult to study in humans because currently available laboratory models use only one daily session during which a single dose or multiple doses are administered. In the present study, seven adult male IV cocaine users completed a protocol investigating changes in cardiovascular and subjective responses during the repeated self-administration of cocaine. Volunteers participated in a 2-day and a 3-day access condition. On each day of access, they participated in two 2.5-h sessions, one at 1200 and another at 1600 hours. In the 2- and 3-day conditions, participants had access to cocaine on 2 or 3 consecutive days, respectively. During sessions, participants could self-administer up to six doses of IV cocaine (32 mg/70 kg) every 14 min. Participants chose not to self-administer cocaine on only 10% of the 420 trials. Acute tolerance developed to the cardiovascular and several subjective effects of cocaine. Heart rate was the only measure that tended to decrease across days of repeated cocaine self-administration. Ratings of “I want cocaine” decreased at the end of the last self-administration session during both 2- and 3-day conditions. There was no difference between the 2- and 3-day conditions for any measure. The laboratory model of “binge” cocaine use established in this study can be used to describe changes in cardiovascular and subjective effects of cocaine within and between bouts of repeated cocaine use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050358
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  • 106
    Electronic Resource
    Electronic Resource
    Human cytochromes mediating N-demethylation of fluoxetine in vitro (1997)
    Springer
    Psychopharmacology 132 (1997), S. 402-407 
    Details
    ISSN: 1432-2072
    Keywords: Key words Fluoxetine ; N-Demethylation ; Cytochromes ; Microsomes ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Biotransformation of the selective serotonin reuptake inhibitor antidepressant, fluoxetine, to its principal metabolite, norfluoxetine, was evaluated in human liver microsomes and in microsomes from transfected cell lines expressing pure human cytochromes. In human liver microsomes, formation of norfluoxetine from R,S-fluoxetine was consistent with Michaelis-Menten kinetics (mean Km = 33 μM), with evidence of substrate inhibition at high substrate concentrations in a number of cases. The reaction was minimally inhibited by coincubation with chemical probes inhibitory for P450-2D6 (quinidine), -1A2 (furafylline, α-naphthoflavone), and -2E1 (diethyldithiocarbamate). Substantial inhibition was produced by coincubation with sulfaphenazole (Ki = 2.8 μM), an inhibitory probe for P450-2C9, and by ketoconazole (Ki = 2.5 μM) and fluvoxamine (Ki = 5.2 μM). However, ketoconazole, relatively specific for P450-3A isoforms only at low concentrations, reduced norfluoxetine formation by only 20% at 1 μM, and triacetyloleandomycin (≥ 5 μM) reduced the velocity by only 20–25%. Microsomes from cDNA-transfected human lymphoblastoid cells containing human P450-2C9 produced substantial quantities of norfluoxetine when incubated with 100 μM fluoxetine. Smaller amounts of product were produced by P450-2C19 and -2D6, but no product was produced by P450-1A2, -2E1, or 3A4. Cytochrome P450-2C9 appears to be the principal human cytochrome mediating fluoxetine N-demethylation. P450-2C19 and -3A may make a further small contribution, but P450-2D6 is unlikely to make an important contribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050362
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  • 107
    Electronic Resource
    Electronic Resource
    Modulating effects of a cold water stimulus on opioid effects in volunteers (1997)
    Springer
    Psychopharmacology 131 (1997), S. 313-320 
    Details
    ISSN: 1432-2072
    Keywords: Key words Morphine ; Butorphanol ; Subjective ; Opiate ; Psychomotor ; Opioid ; Analgesia ; Pain ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of this study was to characterize the effect of a painful stimulus on morphine and butorphanol effects in healthy non-drug abusing volunteers. Thirteen subjects with no history of opiate dependence participated in a randomized, placebo-controlled, double-blind, crossover trial in which each subject received saline, 2 mg/70 kg butorphanol, and 10 mg/70 kg morphine, IV, in each of two conditions, periodic forearm immersions into either ice-cold water (2°C) or into warm water (37°C). Both opioids reduced self-reported ratings of pain intensity, indicative of analgesia. Several of the subjective effects of morphine were attenuated either during or in between cold-water immersions, including visual analog scale ratings of “coasting (spaced out),”“high (drug “high”),”“sleepy (drowsy, tired),” and “lightheaded”. In contrast, some of butorphanol’s subjective effects were increased by the cold-water manipulation. Morphine impaired psychomotor performance during one of the warm-water immersions, but not during the cold-water immersions. Psychomotor impairment induced by butorphanol was not affected by water temperature. This study provides evidence that opioid effects can be modulated by a painful stimulus in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050298
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  • 108
    Electronic Resource
    Electronic Resource
    Effects of haloperidol and amisulpride on motor and cognitive skill learning in healthy volunteers (1997)
    Springer
    Psychopharmacology 131 (1997), S. 329-338 
    Details
    ISSN: 1432-2072
    Keywords: Key words Haloperidol ; Amisulpride ; Human ; Cognitive ; Motor ; Skill learning ; Memory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of a typical neuroleptic, haloperidol (1 and 2 mg orally), of an atypical neuroleptic, amisulpride (50 and 100 mg) and of a placebo on motor and cognitive skill learning were assessed in 60 healthy volunteers using repeated testing on the Tower of Toronto puzzle. Subjects were asked to solve three blocks of eight trials and, at distance from drug administration, a fourth block. The puzzle was connected to a computer in order to obtain a precise timing of individual moves. Two components of cognitive skill learning were assessed, the ability to learn to solve the puzzle and the acquisition of a problem-solving routine. Subjective feelings of effort and automatisation of the task were assessed using a questionnaire. Like placebo-treated subjects, neuroleptic-treated subjects were able to acquire a motor skill, to learn to solve the puzzle and to acquire a routine. However, haloperidol 2 mg-treated subjects needed significantly more moves to solve the puzzle in blocks 3 and 4, some of them having routinised a non-optimal solution. A significant cognitive slowing was observed in the haloperidol 1mg group in block 4. The performance pattern and verbal reports suggested that haloperidol impaired the higher cognitive functions such as the ability to shift from one strategy to another and/or to assess one’s performance accurately, possibly leading to the development of compensatory strategies. The only deleterious amisulpride effect was a cognitive slowing in block 4, which was observed in the lower dose group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050300
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  • 109
    Electronic Resource
    Electronic Resource
    A PET-study of [11C]FLB 457 binding to extrastriatal D2-dopamine receptors in healthy subjects and antipsychotic drug-treated patients (1997)
    Springer
    Psychopharmacology 133 (1997), S. 396-404 
    Details
    ISSN: 1432-2072
    Keywords: Key words [11C]FLB 457 ; D2-dopamine receptors ; Human ; Positron emission tomography ; Neuroleptic drug
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We recently developed [11C]FLB 457 a substituted benzamide with the very high affinity of 20 pM for D2-dopamine receptors in vitro. The aim of the present exploratory study was to examine the anatomical distribution of [11C]FLB 457 binding in the human brain and to determine extrastriatal D2-receptor occupancy in antipsychotic drug-treated patients. [11C]raclopride was used to obtain reference values for D2-dopamine receptor occupancy in the putamen. After IV injection of [11C]FLB 457 there was a high concentration of radioactivity, not only in the caudate putamen but also in the thalamus and the temporal cortex. The concentration of radioactivity in the frontal cortex, the substantia nigra and the colliculi was slightly higher than in the cerebellum. Pretreatment with haloperidol and fluphenazine indicated that [11C]FLB 457 binding in extrastriatal regions to a high degree represents specific binding to D2-dopamine receptors. The D2-occupancy in antipsychotic drug-treated patients was on the same level in the thalamus and the temporal cortex as that determined with [11C]raclopride in the putamen. The study shows that [11C]FLB 457 has potential for quantitative PET-examination of D2-dopamine receptors in man.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050420
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  • 110
    Electronic Resource
    Electronic Resource
    The effects of food deprivation and incentive motivation on blood glucose levels and cognitive function (1997)
    Springer
    Psychopharmacology 134 (1997), S. 88-94 
    Details
    ISSN: 1432-2072
    Keywords: Key words Food deprivation ; Blood glucose ; Cognitive function ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The current study investigated the relationships between blood glucose levels, mild food deprivation, sympathetic arousal, and cognitive processing efficiency. Subjects (n = 82) were randomly assigned to four experimental conditions, comprising combined manipulations of food deprivation and incentive motivation. Baseline and mid-session measurements of blood glucose, blood pressure and pulse rate were taken. Subjects completed a number of measures of cognitive processing efficiency and self report measures of affective and somatic state. Although glucose levels were lowered following food deprivation, there was no significant detrimental effect of food deprivation on task performance. However, improved recognition memory processing times were associated with deprivation. Incentive motivation was associated with faster simple reaction times and higher diastolic blood pressure. There were no significant relationships between glucose levels and task performance, further supporting the hypothesis that the brain is relatively invulnerable to short food deprivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050429
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  • 111
    Electronic Resource
    Electronic Resource
    Age-related differences in the temporal and spatial regulation of matrix metalloproteinases (MMPs) in normal skin and acute cutaneous wounds of healthy humans (1997)
    Springer
    Cell & tissue research 290 (1997), S. 581-591 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Ageing ; Skin ; Proteinase ; Wound ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Despite the association of increasing age with chronic wound-healing disorders and an impaired rate of healing of acute cutaneous wounds, the role of matrix metalloproteinases (MMPs) is unknown. To determine the spatial and temporal patterns and activities of MMP-1, -2, -3 and -9, 132 healthy humans aged between 19 and 96 years underwent 4-mm punch biopsies followed by wound excision between day 1 and day 180 post-wounding. Wounds showed an age-related increase in MMP-2 and MMP-9 immunostaining from day 3; this was associated with degradation of gelatin as shown by zymograms and with increased proteinase activity as shown by azocoll assays. Distinct spatial localisations for each MMP were observed: MMP-2 was found in epidermal structures; MMP-9 was observed in inflammatory cells up to day 21; MMP-1 was localised to keratinocytes at the wound margin. Normal old skin showed pro-MMP-2 bands on zymography and increased MMP-2 immunostaining. These results indicate that: (1) intrinsic ageing is associated with the up-regulation of MMPs previously associated with chronic wound healing; (2) wound-tissue proteinases are essentially active up to day 21 postwounding; and (3) intrinsic ageing may predispose to tissue breakdown disorders because of MMP-2 up-regulation in normal skin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050963
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  • 112
    Electronic Resource
    Electronic Resource
    The fibroblast-specific MAb AS02: a novel tool for detection and elimination of human fibroblasts (1997)
    Springer
    Cell & tissue research 290 (1997), S. 593-599 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Fibroblast-specific antibody ; Fibroblast separation and elimination ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The unwelcome presence of fibroblasts in many cell cultures prevents the long term cultivation of various cell types and work with pure populations. Recently, we described a novel fibroblast-specific monoclonal antibody (MAb AS02) that recognises a membrane-bound antigen. We have now developed a method using the fibroblast-specific MAb AS02 immobilised on goat-anti-mouse-magnetic beads to separate contaminating fibroblasts. An endothelial cell line experimentally contaminated with 5%–50% fibroblasts was successfully purified. Additionally, an endothelial cell line with an initial fibroblast contamination of 1.5% was prepared. A proportion of each preparation was cultured with no separation step being performed, whereas the remainder was cultured after purification with MAb AS02 to exclude the presence of a minor number of fibroblasts (〈0.1%). The proportion of fibroblasts increased up to 38% in the fifth passage of culture without elimination of the low initial fibroblast contamination, whereas in the fraction with the separation step, no fibroblasts were detectable by flow cytometry, even after the fifth passage. We also used the antibody to detect the presence of naturally contaminating fibroblasts in thyrocyte cultures. After cultivation of thyrocyte cultures over five passages, the number of fibroblasts increased dramatically up to 50%–80% of the whole population. Subsequently, we successfully applied the method for complete elimination of naturally contaminating fibroblasts from freshly isolated thyrocyte cultures from enzymatically digested thyroid glands. Thus, MAb AS02 is a fibroblast-specific marker that is a useful tool for the detection and elimination of contaminating fibroblasts. The specificity of MAb AS02 permits the universal application of this antibody for human cell cultures of interest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050964
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  • 113
    Electronic Resource
    Electronic Resource
    Light-microscopical investigation of the distribution of extracellular matrix molecules and calcifications in human dental pulps of various ages (1997)
    Springer
    Cell & tissue research 289 (1997), S. 145-154 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Teeth ; Dental pulp ; Immunohistology ; Extracellular matrix ; Collagen ; Aging ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The distribution of extracellular matrix molecules, especially collagen types I, III, V, and VI, in the extracellular matrix of the connective tissue of human dental pulp of various ages was studied by polarization and indirect immunofluorescence microscopy by using a conventional fluorescence microscope and a confocal laser scanning microscope. Polarization and immunofluorescence microscopy of paraffin sections showed thick fibers of collagen type I, which represented the main component of the connective tissue matrix of the dental pulp. By indirect immunofluorescence, thin fibers and small bundles of collagen type III were determined to be one of the main fibrillar elements present in the dental pulp matrix. Collagen type IV was detected by a clear intense staining of the basement membrane of blood vessels at all ages examined. Collagens type V and VI formed a dense meshwork of thin microfibrils throughout the stroma of the connective tissue of the dental pulp. These fibers were localized around blood vessels and appeared to be enriched in the subodontoblastic layer. Investigations by means of confocal laser scanning microscopy revealed fibers of collagen type VI spiralling between fully differentiated odontoblasts toward the predentin layer. With advancing age, the connective tissue matrix appeared to be condensed and aggregates of thick fiber bundles could be observed. Furthermore, the participation of various collagen types in the composition of pulp stones was shown. These calcifications and diffuse calcifications increased in frequency with advancing age in a statistically significant manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050860
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  • 114
    Electronic Resource
    Electronic Resource
    Immunohistochemical localization of the small proteoglycans decorin and biglycan in human intervertebral discs (1997)
    Springer
    Cell & tissue research 289 (1997), S. 185-190 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Small proteoglycans ; Intervertebral disc ; Decorin ; Biglycan ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Immunohistochemistry was used to study the presence and distribution of the core proteins of the small proteoglycans decorin and biglycan in the various compartments of human intervertebral discs. Both proteoglycans could be found in the outer tendon-like parts of the annulus fibrosus, indicating their potential role in collagen network formation and biomechanical stress resistance. The loss of both proteoglycans in the annulus of individuals older than 50 years reflects a normal age-related change. In the nucleus pulposus, decorin could be found in fibrillar areas of the interterritorial matrix, thereby indicating co-localization of decorin with fibrils containing type II collagen. Biglycan was present in the extracellular matrix of the nucleus pulposus of adults. The pericellular immunoreactive rims observed around nucleus pulposus cells and giant chondrones indicated local biosynthetic activity for these small proteoglycans. The staining patterns in cartilage endplates resembled those found in human hyaline articular cartilage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050864
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  • 115
    Electronic Resource
    Electronic Resource
    Differential distribution of five members of the matrix metalloproteinase family and one inhibitor (TIMP-1) in human liver and skin (1997)
    Springer
    Cell & tissue research 289 (1997), S. 173-183 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Collagen ; Matrilysin (PUMP) ; Wound healing ; Tumors ; Fat-storing cells ; Peripheral nerve glial cells ; Fibrocytes ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Matrix metalloproteinases represent a family of zinc-dependent proteolytic enzymes thought to be involved in normal and disease-related tissue remodeling processes. Increasing information about these enzymes is becoming available concerning their primary sequences, regulation at the mRNA level, activation of proenzymes, and modulation of enzyme activity by tissue inhibitors. In contrast, their morphological distribution and biological functions in normal tissues are poorly understood. In the present report, the comparative distribution of five members (gelatinase-A, gelatinase-B, matrilysin, stromelysin-1, and stromelysin-3) of the matrix metalloproteinase family and of one inhibitor (TIMP-1) has been morphologically analyzed in human liver and skin with the aid of new monospecific antibodies. Because of their common designation as matrix proteinases, these enzymes might have been expected to be distributed throughout these tissues, or at least in the connective tissue. However, each member of the family produces a highly specific pattern, staining structures such as arteriolar smooth muscle cells, myoepithelial cells in secretory portions or the luminal lining in excretory ducts of dermal sweat glands, liver bile canaliculi, or structures surrounding peripheral nerve axons. No reactivity is detected in rat tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050863
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  • 116
    Electronic Resource
    Electronic Resource
    GDNF improves survival and reduces apoptosis in human embryonic dopaminergic neurons in vitro (1997)
    Springer
    Cell & tissue research 289 (1997), S. 207-210 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Parkinson’s disease ; Programmed cell death ; Dopamine ; Growth factors ; Neurotransplantation ; Glia ; Human ; Bonnet monkey ; Macaca radiata (Primates)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Dopamine cell death is the primary problem limiting the value of neurotransplantation in human patients with Parkinson’s disease. To address this problem, we added glial cell line-derived neurotrophic factor (GDNF) to cultures of embryonic dopaminergic neurons obtained from human and from Bonnet monkey (Macaca radiata) in an effort to reduce apoptotic cell death and improve overall cell survival. Tissue from three human embryos, 7–8 weeks post-conception, and one 9-week post-conception monkey embryo were dissociated and cultured in F-12 media with 5% human placental serum. GDNF (10 ng/ml) in human cultures nearly doubled dopamine neuron survival and reduced the rate of apoptosis from 6% to 3%. In monkey cultures, GDNF also enhanced dopamine neuron survival and reduced the apoptotic rate. We conclude that GDNF improves the survival of primate embryonic dopamine neurons in culture by reducing apoptosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050867
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  • 117
    Electronic Resource
    Electronic Resource
    Coordinated change between complement C1s production and chondrocyte differentiation in vitro (1997)
    Springer
    Cell & tissue research 289 (1997), S. 299-305 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Complement C1s ; Sandwich ELISA ; Chondrocytes ; Cell culture ; Differentiation ; Ascorbic acid ; Syrian hamster ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. In vitro synthesis of the first component of complement C1s was examined by using hamster epiphyseal chondrocytes (HAC) and human chondrosarcoma cell line HCS-2/8. Hamster and human C1s produced by the cells were quantified by immunoblotting and sandwich enzyme-linked immunosorbent assay (ELISA), respectively. It was possible to measure active and inactive C1s by sandwich ELISA, when we used anti-human C1s monoclonal antibodies, M241 recognizing only active C1s, and M365 and M81 recognizing both active and inactive C1s. Approximately 40% of C1s secreted from HCS-2/8 was found to be activated in the culture medium, whereas C1s from HAC was not. C1s production increased in accordance with chondrocyte differentiation induced by ascorbic acid. In contrast, transforming growth factor-beta1 and basic fibroblast growth factor, which inhibited differentiation, suppressed C1s production. These results confirmed our previous observation showing that C1s synthesis increased with differentiation into hypertrophic chondrocytes in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050876
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  • 118
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    Development of striated rootlets during ciliogenesis in the human oviduct epithelium (1997)
    Springer
    Cell & tissue research 290 (1997), S. 39-42 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Ciliogenesis ; Striated rootlets ; Oviduct ; Ciliated cells ; Ultrastructure ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Striated rootlets in ciliated cells are conical banded structures composed of longitudinally aligned filaments. The formation of striated rootlets during ciliognesis in the human oviduct epithelium was studied by electron microscopy. Primitive rootlets appeared at the proximal side of basal bodies before or at the same time as ciliary budding. After the formation of several striations, the tip of the rootlets extended deeply toward the interior of the cell and became differentiated into two distinct parts, viz., the proximal conical part connected to the basal body and the distal fibrillar part. The periodicity of the striations in the fibrillar part was 68.5±2.95 nm, about 5 nm longer than that of the conical part (63.9±2.25 nm). The dark band in the striation was thicker in the fibrillar part than in the conical part. Since the fibrillar part was not observed in the mature cilium, this part was considered as being either degraded or changed into the conical part during ciliogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050905
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  • 119
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    Platelet/endothelial cell adhesion molecule-1 (PECAM-1) is localized over the entire plasma membrane of endothelial cells (1997)
    Springer
    Cell & tissue research 290 (1997), S. 623-631 
    Details
    ISSN: 1432-0878
    Keywords: Key words: PECAM-1 (platelet/endothelial cell adhesion molecule-1) ; Endothelium ; HUVEC (human umbilical vein endothelial cells) ; Myocardium ; Ultrastructure ; Human ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The subcellular localization of PECAM-1 in endothelial cells was examined by using advanced morphological techniques, such as confocal scanning microscopy and immunolabeling procedures for electron microscopy. The localization of PECAM-1 was studied immunohistochemically with five specific monoclonal antibodies and one polyclonal antibody (all anti-human) in human and rabbit myocardium and in isolated endothelial cells. In vivo, PECAM-1 was localized uniformly on the plasma membrane of all vascular endothelial cells, predominantly on the luminal side of vessels. No specific increase in labeling was found at sites of cell-to-cell contact. In vitro, primary isolated cells (human umbilical vein endothelial cells) showed continuous labeling of the entire cell membrane. Cells of higher passages were labeled in a manner similar to freshly isolated cells. Our findings refute the commonly accepted hypothesis that PECAM-1 is localized only at cell-to-cell contacts. Further, we have not been able to confirm the hypothesis regarding the important mechanical role of PECAM-1 in stabilizing the endothelial monolayer. Since PECAM-1 is also expressed on platelets and is known to bind to itself, the way in which PECAM-1-positive endothelial cells are protected against binding of PECAM-1-positive platelets remains unclear. In view of these findings, the role of PECAM-1 in the leukocyte migration cascade needs to be re-evaluated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050968
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  • 120
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    Immuno-electron microscopy reveals that the excitotoxin quinolinate is associated with the plasma membrane in human peripheral blood monocytes/macrophages (1997)
    Springer
    Cell & tissue research 290 (1997), S. 633-639 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Quinolinic acid ; Interferon-γ ; Kynurenine ; Electron microscopy ; Immunocytochemistry ; Excitotoxicity ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract.  Quinolinate (QUIN), a tryptophan-derived excitotoxin, was localized ultrastructurally in human peripheral blood monocytes/macrophages (MØ) by immuno-electron microscopy. A combined carbodiimide/glutaraldehyde/paraformaldehyde-based fixation procedure was developed for optimal retention of QUIN in the cell as well as minimal loss of ultrastructure; a silver-enhanced colloidal gold detection system was used for electron-microscopic analysis. Gold particles representing QUIN immunoreactivity were associated with the inner side of the plasma membrane in normal MØ. The number of gold particles increased significantly when QUIN levels were elevated by treatment with its precursor kynurenine, but location of the gold particles remained essentially the same under this condition. Treatment with interferon-γ increased the number of Golgi bodies, vacuoles and pseudopodia, reflecting the activated state of the cell. Significantly increased numbers of gold particles representing QUIN were detectable in approximately the same location as in the case of kynurenine treatment. Combined treatment with kynurenine and interferon-γ maximally increased the number of gold particles at the periphery of the cell. The pseudopodia were intensely stained with gold particles, while they were not detectable in the inner part of the cytoplasm or in any other organelle even under this activated condition. The significance of the specific location of QUIN revealed in the present study and its relation to the release and subsequent actions of QUIN are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050969
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  • 121
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    Immunohistochemistry of matrix metalloproteinases (MMP), their substrates, and their inhibitors (TIMP) during trophoblast invasion in the human placenta (1997)
    Springer
    Cell & tissue research 291 (1997), S. 133-148 
    Details
    ISSN: 1432-0878
    Keywords: Key words Placenta ; Extravillous trophoblast ; Matrix-type fibrinoid ; Extracellular matrix ; MMP ; TIMP ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The invasion of extravillous trophoblast cells into the maternal endometrium is one of the key events in human placentation. The ability of these cells to infiltrate the uterine wall and to anchor the placenta to it as well as their ability to infiltrate and to adjust utero-placental vessels to pregnancy depends, among other things, on their ability to secrete enzymes that degrade the extracellular matrix. Most of the latter enzymes belong to the family of matrix metalloproteinases. Their activity is regulated by the tissue inhibitors of matrix metalloproteinases. We have studied the distribution patterns of matrix metalloproteinases-1, -2, -3, and -9 and their inhibitors TIMP-1 and TIMP-2 as compared to the distribution of their substrates along the invasive pathway of extravillous trophoblast of 1st, 2nd, and 3rd trimester placentas by means of light microscopy on paraffin and cryostat sections as well as at the ultrastructural level (only 3rd trimester placenta). The comparison of different methods proved to be necessary, since the immunohistochemical distribution patterns of these soluble enzymes are considerably influenced by the pretreatment of tissues. All three methods revealed immunoreactivities of both, proteinases and their inhibitors, not only intracellularly in the extravillous trophoblast but also extracellularly in its surrounding matrix, the distribution patterns depending on the stage of pregnancy and on the degree of differentiation of trophoblast cells along their invasive pathway. Within the extracellular matrix, immunolocalization of matrix metalloproteinases as well as their inhibitors showed a specific relation to certain extracellular matrix molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050987
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  • 122
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    Distribution and subcellular localization of a lysosome-associated protein in human genital organs (1997)
    Springer
    Cell & tissue research 287 (1997), S. 335-342 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Lysosomal membrane antigen ; Immunohistochemistry ; Biosynthesis ; Prostate-membrane-specific antigen ; Apocrine secretion ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The tissue distribution, preferentially in the human male genital system, and the subcellular localization of the lysosome-associated membrane protein 2 (lamp 2) was studied immunohistochemically using a mouse monoclonal antibody, 2D5. Strong immunoreactivity was present in the tubular system of the kidney, in acinar cells of salivary glands and pancreas, prostate, mammary glands, placenta and in cutaneous sweat glands. Moderate immunoreactivity was observed in cerebral neuronal cells, epidermal cells, testis, epididymis, seminal vesicle and endometrium. Very low immunoreactivity was found in liver. In some of the tissues mentioned, the distribution pattern of immunoreactivity is smooth and homogeneous, while in others it is granular and concentrated in the supra- or perinuclear cytoplasm. The subcellular distribution was studied on ultracryosections and on pre-embedding-processed chopper sections of human prostate. In the latter gland, the protein is not restricted to epithelium, but is also present in stromal cells. Ultrastructurally, the immunoreactivity in secretory cells was localized in electron-translucent vacuoles and granules, including the secretory granules. A close association with cell membranes was not generally the case. Only part of the immunoreactive material was linked to the apical plasma membrane pointing to a biosynthesis independent from an association step with the apical plasma membrane. As shown by immunoelectron microscopy and Western blotting, a high amount of lamp 2 is secreted and is found in so-called prostasomes. The findings indicate that in the human prostate most of the membrane-bound lamp 2 is released from the secretory cells, presumably in an apocrine fashion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050758
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    Occurrence of enzymes of free radical metabolism suggests the possible cytotoxic capacity of the transitional epithelium of the human ureter (1997)
    Springer
    Cell & tissue research 287 (1997), S. 351-356 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Urothelium ; Tartrate-resistant acid phosphatase ; Nitric oxide synthase I ; Superoxide dismutase ; Immunocytochemistry ; Free radicals ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Three enzymes, viz., tartrate-resistant acid phosphatase (TRAP), nitric oxide synthase I (NOS-I), and superoxide dismutase (SOD), involved in the production and metabolism of free radicals or radical equivalents, were demonstrated by immunocytochemistry in the urothelium of the ureters of six patients of various ages. Two of these enzymes (TRAP and NOS-I) were colocalized in the most apical and lateral border of the superficial cells of the urothelium. In contrast, SOD showed a patchy or granular distribution within the supranuclear region of these cells. Intra- and subepithelial macrophages exhibited a weak TRAP, but no NOS-I or SOD, immune reaction. On the basis of the immunocytochemical findings, arguments in favor of a cytotoxic function of the superficial cells of the human urothelium are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050760
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  • 124
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    Number and size of epineurial blood vessels in normal and diseased human sural nerves (1997)
    Springer
    Cell & tissue research 290 (1997), S. 31-37 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Sural nerve ; Blood vessels ; Angiopathic neuropathy ; Vasculitis ; Peripheral neuropathy ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The number and dimensions of epineurial blood vessels in normal human sural nerves have, thus far, not been determined using systematic, reproducible morphometric methods, although this nerve is most frequently used for diagnostic biopsies. Quantitative changes in epineurial blood vessels appear to be major parameters for identifying angiopathy and angiopathic peripheral neuropathy. Therefore, we examined the epineurial blood-vessel number in relation to the age of the patients and to the number and size of the nerve fascicles in each of 51 human sural nerve biopsies. The data from a control group were compared with pathological cases. We found that the number of epineurial blood vessels (normal mean: 57.7) increased significantly (up to 196) in biopsies where there were signs of angiopathy (P≤0.01) or vasculitis (P≤0.05). The increase in the number of epineurial blood vessels usually resulted from a proliferation of capillaries. The fascicular cross-sectional area did not appear to be related to the number of epineurial blood vessels, although it increased significantly in cases with vasculitis (P≤0.05) or an axonal type of neuropathy (P≤0.05). Thus, this study shows that the number of epineurial blood vessels is a helpful parameter in verifying angiopathy and angiopathic peripheral neuropathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050904
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  • 125
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    A model system for long-term serum-free suspension organ culture of human fetal tissues: experiments on digits and skin from multiple body regions (1997)
    Springer
    Cell & tissue research 290 (1997), S. 51-60 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Serum-free culture medium ; Organ culture ; Fetal digits ; Fetal skin ; Nails ; Hair follicles ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. We have optimized a suspension organ culture (SOC) system previously used to study human fetal skin in vitro. Eleven types of media were used to culture fetal digits and skin samples (ranging from 59–91 days of estimated gestational age) for periods of 3 or 4 weeks. The cultures were supplemented with 0%–10% bovine calf serum and exposed to 5%–45% oxygen atmospheres. Optimal conditions, which were selected based upon the morphologic and histologic properties of the cultured tissues, were: DMEM-F12 medium in a serum-free environment with a 45% oxygen atmosphere. The refined SOC system supports the maintenance and/or continued development of the epidermis and dermis of trunk, back, scalp, and digital skin, developing hair follicles, nails, and glands. Overall, development and differentiation mimicked the in vivo state more closely than that observed when using other in vitro culture systems. The effects of bovine calf serum and oxygen levels are presented, and the potential for manipulating the environment of this system for studying mechanisms of cutaneous development is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050907
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  • 126
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    Molecular anatomy of the perivascular sheath in human placental stem villi: the contractile apparatus and its association to the extracellular matrix (1997)
    Springer
    Cell & tissue research 290 (1997), S. 601-607 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Placental stem villi ; Perivascular contractile sheath ; Molecules of adhesion plaques ; Extracellular matrix molecules ; Immunocytochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. In previous studies, we have shown that smooth muscle cells and myofibroblast subpopulations of the perivascular stem villous sheath of the human placenta contain focal adhesion plaques and talin immunoreactivity. The close association of these cells to elastic and collagen fibres have led to the assumption of a functional myofibroelastic unit within the perivascular stem villous sheath. Interactions between the extracellular matrix and smooth muscle cells depend on a variety of structural protein assemblies. In the present study, we examined, by immunocytochemistry, whether the molecular assembly of extracellular matrix proteins and molecules of focal adhesions, known to be essential for signal transduction in smooth muscle cells, are also found in smooth muscle cells of the perivascular stem villous sheath of the human placenta. Vascular and extravascular smooth muscle cells were immunoreactive for α-actinin, vinculin, paxillin and tensin, the integrin chains α1 and β1, and the basement membrane components laminin and heparan/-chondroitin sulfate proteoglycan perlecan. pp125FAK did not react. In the extracellular matrix of blood vessel walls and the perivascular stem villous sheath, we found immunoreactivity of fibronectin and collagen types I, VI and undulin (collagen type XIV). From our data we conclude that within the perivascular stem villous sheath, there exists a system of signal transduction molecules, indicating a cross talk between the smooth muscle cells of this sheath and their surrounding extracellular matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050965
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    Human follicular dendritic cells in vitro and follicular dendritic-cell-like cells (1997)
    Springer
    Cell & tissue research 288 (1997), S. 381-389 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Germinal center ; Follicular dendritic cells ; Cell culture ; Adhesion and co-stimulatory molecules ; Emperipolesis ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Human follicular dendritic cell (FDC)-like cells (FLC) have been utilized for the in vitro analysis of germinal center reactions. However, there is no consensus whether FLC represent FDC in vitro. The purpose of the present study has therefore been to determine distinguishing features of FDC and FLC in vitro. The expression of CD40, CD54, CD49d, cytokine (γ-IFN and IL-4)-dependent MHC-class II, and CD106 was observed to be specific for the determination of FDC in long-term culture. The cytokine-dependent emperipolesis of germinal center B cells was establised as another discriminating property for FDC in vitro. In 2 out of 72 long-term cultures of FDC, we encountered dividing cells among the non-dividing population of FDC. The dividing cells expressed accessory molecules similar to those of FDC but showed emperipolesis only for the initial few days of their growth. FDC did not enhance the CD40-dependent proliferation of germinal center B cells; in contrast, FLC augumented it. Both types of cells produced a significant amount of cytokine-dependent IL-6. Further studies are needed to determine whether FLC originate from FDC in vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050824
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    Angioarchitecture of the human spermatic cord (1997)
    Springer
    Cell & tissue research 288 (1997), S. 391-398 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Spermatic cord ; Pampiniform plexus ; Arterio-venous anastomoses ; Casting preparations ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Human spermatic cords were investigated by means of cast preparations, light-microscopic examination and computer-aided 3-dimensional reconstructions from serial sections of paraffin-embedded material. After leaving the testis, the testicular veins formed two principal groups co-existing side by side. Numerous veno-venous anastomoses could be observed within each individual group, whereas only a few mutual intergroup anastomoses were found. The testicular artery ran within one group but showed no close topographical relationship to the other group. Light microscopy of the serial sections revealed that the group of veins with no close topographical relationship to the testicular artery ran at a distance of several centimeters embedded within fatty tissue. With the help of computer-aided 3-dimensional reconstructions, a spatial picture of the vascular organization was obtained. These results allowed the following classification of the veins of the pampiniform plexus. Group-I veins formed a tight plexus around the testicular artery by means of veno-venous anastomoses. Group-II veins formed veno-venous anastomoses between each other and ran over at a sizeable distance embedded in fatty tissue but showed no close topographical relationship to the testicular artery. Group-III vessels formed veno-venous anastomoses between group-I and group-II. Group IV veins formed arterio-venous anastomoses with the testicular artery. Based on the differences in wall structure and diameter, a subclassification in group-I and group-II was undertaken. This organization of the veins of the human pampiniform plexus should further the understanding of physiological processes, such as the transfer of hormones and other substances from the veins to the testicular artery and vice versa. It should also facilitate the tracing of the veins during antegrade sclerosing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050825
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    Distribution of heat-shock protein 60 immunoreactivity in testes of infertile men (1997)
    Springer
    Cell & tissue research 288 (1997), S. 539-544 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Testis ; hsp60 ; Infertility ; Spermatogonia ; Immunohistochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The immunohistochemical localization of heat-shock protein 60 (hsp60) was investigated in testicular biopsies obtained from 121 adult men with disturbed fertility. In normal unaffected tubules, hsp60 immunoreactivity was localized to spermatogonia, primary spermatocytes and Sertoli cells. In spermatogonia, cytosolic and mitochondrial labelling could be differentiated. In general, the number of stained spermatogonia decreased with the loss of spermatogenic function. A significant (P〈0.01) reduction of stained spermatogonia was observed in testes with maturation arrest of spermatogenesis at the level of primary spermatocytes (30.2±21.6%) compared with testes exhibiting normal spermatogenesis. In addition, the decrease in the score correlated significantly with the diminution of cytosolic hsp60 immmunolabelling (coefficient r=0.25, P=0.03). There was a significant difference (P〈0.01) in the percentage of cytosolic-stained spermatogonia in testes with a score equal to or greater than 5 (14.7±9.8%) and a score less than 5 (8.9±6.9%). These observations suggest that a low level of hsp60 expression in spermatogonia may lead to a different pattern of protection, which in turn could be involved in low spermatogenic efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050839
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  • 130
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    Complement Cls, a classical enzyme with novel functions at the endochondral ossification center: immunohistochemical staining of activated Cls with a neoantigen-specific antibody (1997)
    Springer
    Cell & tissue research 288 (1997), S. 557-565 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Complement Cls ; Neoantigen ; Cartilage ; Hypertrophic chondrocyte ; Immunohistochemistry ; Rheumatoid arthritis ; Decorin ; Syrian hamster ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The secondary ossification center of 14- to 16-day-old hamster tibiae was examined immunohistochemically with active and inactive Cls-specific antibodies, RK5 and RK4, respectively. At the ossification center, chondrocytes differentiate from proliferating and hypertrophic to degenerating stages, and their site is occupied by the bone marrow. Cls was strongly immunostained in hypertrophic chondrocytes. In order to discover whether Cls is activated at a particular site, the cartilage was immunostained with RK5 and RK4. RK5 mainly reacted with degrading matrix around invading vessels. In contrast, RK4 strongly stained hypertrophic chondrocytes. Immunoelectron microscopy revealed Cls on degrading fragments of chondrocytes and fibers of cartilage matrix. Decorin, one of the major matrix proteoglycans, was dose and time dependently degraded by Cls. Type II collagen and type I gelatin were also degraded. Articular cartilage from patients with rheumatoid arthritis was positively immunostained (11/12 cases) with an anti-Cls monoclonal antibody (mAb) PG11, whereas normal articular cartilage (5/5 cases) was negative, suggesting Cls participation in the etiology of rheumatoid arthritis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050841
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    Distribution of neuropeptide-containing nerve fibers in the human submandibular gland, with special reference to the difference between serous and mucous acini (1997)
    Springer
    Cell & tissue research 288 (1997), S. 25-31 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Submandibular gland ; Neuropeptide Y ; Vasoactive intestinal polypeptide ; Galanin ; Substance P ; Calcitonin gene-related peptide ; Immunohistochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Distribution of neuropeptide Y (NPY)-, vasoactive intestinal polypeptide (VIP)-, galanin (GAL)-, substance P (SP)-, and calcitonin gene-related peptide (CGRP)-immunoreactive nerve fibers in the human submandibular gland was examined by the peroxidase-antiperoxidase method with attention to high-quality fixation and the condition of patients. NPY-, VIP-, and GAL-immunoreactive varicose fibers were densely distributed around the acini and ducts. Some of these fibers extended between acinar cells. The density of SP- and CGRP-immunoreactive fibers was relatively low. The number of NPY-, VIP-, and GAL-immunoreactive fibers around the mucous acini was significantly higher than around the serous acini. In the perivasculature, NPY-immunoreactive fibers were more numerous than other immunoreactive fibers. No somatostatin-, leucine-, or methionine-enkephalin-immunoreactive fibers were detected. Our findings suggest that a large number of periacinar VIP-, NPY-, and GAL-immunoreactive fibers may participate in regulating the synthesis of saliva and its secretion. Since the VIP-, NPY-, and GAL-immunoreactive fibers are more numerous around the mucous acini than around the serous ones, these fibers may take part more actively in regulating the secretory mechanisms in the mucous acini than in the serous ones. The relatively low number of CGRP- and SP-immunoreactive fibers suggests that they are less involved in the function of the human submandibular gland. Perivascular peptidergic fibers, especially NPY-immunoreactive fibers, may be involved in controlling local blood flow in this gland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050789
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    Fine structure and distribution of lymphatic vessels in the human dental pulp: a study using an enzyme-histochemical method (1997)
    Springer
    Cell & tissue research 288 (1997), S. 79-85 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Lymphatic vessels ; Blood vessels ; Dental pulp ; 5′-nucleotidase ; Alkaline phosphatase ; Enzyme histochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The existence of lymphatic vessels in the human dental pulp and their distribution were established by light and electron microscopy using an enzyme-histochemical method. The distinction between lymphatic and blood vessels was made by light microscopy on cryostat sections of undecalcified and decalcified teeth using 5′-nucleotidase(5′-Nase)-alkaline phosphatase double staining. On the tissue surface, 5′-Nase-positive lymphatic vessels were highlighted with good contrast and resolution by backscattered electron imaging using scanning electron microscopy. By transmission electron microscopy, dense granular precipitations resulting from the 5′-Nase reaction were seen on the luminal surface of the lymphatic endothelial cells as well as in the area at the basal side, but were absent in the blood vessels. These lymphatic vessels were more numerous in the central part than in the peripheral odontoblastic layer.
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    URL: http://dx.doi.org/10.1007/s004410050794
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    Characterization of adult human heart fibroblasts in culture: a comparative study of growth, proliferation and collagen production in human and rabbit cardiac fibroblasts and their response to transforming growth factor-beta1 (1997)
    Springer
    Cell & tissue research 288 (1997), S. 87-93 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Cardiac fibroblasts ; Cell culture ; Growth ; Proliferation ; Collagen production ; Tranforming growth factor-beta1 ; Human ; Rabbit (New Zealand)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Fibroblasts constitute the majority of non-myocyte cells in the heart, but little is known about the biology of human cardiac fibroblasts. We have cultured and characterized fibroblasts from young adult human heart and compared their biological features with those of cells obtained from the ventricular tissue of sex- and developmental-stage-matched rabbits. Cell morphology and growth was determined by light microscopy and by measuring protein synthesis. The proliferative capacity of cells was determined by measuring the doubling time and the level of incorporation of 3H-thymidine into DNA under normal conditions of cell culture and in response to several growth factors. Production of collagen type I was determined at the mRNA level by assessing the steady state level of pro α1 20(l) collagen mRNA in cardiac fibroblasts under normal culture conditions and in response to transforming growth factor-beta (TGF-β), and at the protein level by immuno-slot blot analysis. Ventricular tissue from adult human heart was used successfully for the preparation of passagable (up to nine passages) cultured cardiac fibroblasts. They had a significantly larger surface area per cell than rabbit cells. Under normal culture conditions, they showed a lower rate of DNA synthesis and longer doubling time than rabbit cardiac fibroblasts at the matching passage. The magnitude of growth-factor-induced changes in the incorporation of 3H-thymidine into DNA was lower in human cells than in rabbit cardiac fibroblasts, as was the level of mRNA for pro α1(l) collagen. The TGF-β1-induced increase in pro α1(l) collagen mRNA was modest in human cardiac fibroblasts. Thus, significant differences exist between the biological properties of human and rabbit cardiac fibroblasts in culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050795
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    Insulin-like growth factor-I stimulates in vitro migration of preosteoclasts across bone endothelial cells (1997)
    Springer
    Cell & tissue research 288 (1997), S. 101-110 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Insulin-like growth factor-1 (IGF-I) ; Bone endothelial cells ; Preosteoclasts ; Co-culture ; Cell migration ; Electron microscopy (transmission and scanning) ; Bovine ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Little is known about the factors and the mechanisms involved in preosteoclast emigration from the vasculature. In this study, an in vitro model of bone endothelial lining was mimicked by culturing bone endothelial (BBE) cells at confluence on a 3-μm pore polycarbonate membranes. Preosteoclastic (FLG 29.1) cells were then added on top of the BBE cell monolayer and 10 nM insulin-like growth factor-1 (IGF-I) was added below the supporting membrane. Scanning and transmission electron microscopy were used to evaluate the chemotactic responses of preosteoclastic FLG 29.1 cells towards the IGF-I generated gradient. IGF-I potently stimulated chemotaxis in the FLG 29.1 cells, as shown by the migration of the preosteoclastic cells across the underlying BBE and through the intercellular junctions between adjacent endothelial cells. Subsequently, FLG 29.1 cells penetrated the pores of the supporting membrane and reached the lower face of the membrane. Thus, IGF-I, which is abundantly present in the bone tissue microenvironment, may play a paracrine role in the recruitment of the circulating preosteoclasts from the vascular compartment into the bone tissue. This in vitro model, which mimicks the in vivo phenomenon of preosteoclast extravasation, should prove useful in elucidating the molecular mechanisms that underlie this process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050797
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  • 135
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    Human cornea and sclera studied by atomic force microscopy (1997)
    Springer
    Cell & tissue research 288 (1997), S. 111-118 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Cornea ; Sclera ; Collagen ; Extracellular matrix ; Atomic force microscopy ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The purpose of this study was to investigate the ultrastructure of the extracellular matrix of human cornea and sclera by using the atomic force microscope (AFM). Specimens of human cornea (n=16) and sclera (n=10) were obtained from a cornea bank or from enucleated eyes (n=1; clinical and histopathological diagnosis: choroidal melanoma) and fixed in Karnovsky solution. The AFM resolved individual collagen fibrils in corneal and scleral tissue. Scleral collagen fibrils had a diameter ranging from 118.3 to 1268.0 nm and showed clear banding with a mean axial D-periodicity of 77.02 nm. The mean gap depth between the two overlaps was larger in the sclera than in the cornea. The diameter of corneal collagen fibrils ranged from 48.0 to 113.0 nm. In contrast to the sclera, the corneal collagen fibrils did not exhibit clear banding as their surface pattern. Closely attached fibrils with a beaded to globular structure were predominant in the cornea. The mean axial D-periodicity of the corneal collagen fibrils was 68.50 nm. In both tissues, the AFM resolved structures resembling cross-bridges between adjacent fibrils. The corneal collagen fibrils showed fibrillar properties that were different from those of the sclera, and that therefore might be essential for the spatial organization responsible for the optical quality of the cornea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050798
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  • 136
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    Potent inhibition of interleukin-6 expression in a human astrocytoma cell line by tenidap (1997)
    Springer
    Cell & tissue research 288 (1997), S. 251-257 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Interleukin-6 ; Interleukin-1β ; Tenidap ; Astrocytes ; Alzheimer’s disease ; Therapy ; Cell culture ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Tenidap is a structurally novel antirheumatic agent with anti-inflammatory and analgesic properties. Previous studies have shown that tenidap is able to inhibit the production and action of cytokines such as interleukin-1, interleukin-6 (IL-6) and tumour necrosis factor α. However, the mechanisms by which tenidap inhibits cytokine synthesis are not yet known. We investigated in the human astrocytoma cell line U373 whether tenidap inhibits IL-6 synthesis by inhibition of certain signal transduction processes leading to IL-6 synthesis. Cells were stimulated with different substances which have previously been shown to activate protein kinase A or C, reactive oxygen intermediates as well as transcription factors such as nuclear factor kappa B and AP-1 and which all result in IL-6 synthesis. Tenidap was a very potent inhibitor of IL-6 synthesis independent of the stimuli used, suggesting an inhibitory mechanism other than inhibition of a certain signal transduction pathway. Since IL-6 has been shown to be involved in the etiopathology of Alzheimer’s disease and since the use of nonsteroidal anti-inflammatory drugs appears to be of therapeutical benefit, it is concluded that tenidap should be tested in clinical trials in order to determine whether it may be useful for the treatment of Alzheimer’s disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050810
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  • 137
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    E-cadherin and P-cadherin have partially redundant roles in human epidermal stratification (1997)
    Springer
    Cell & tissue research 288 (1997), S. 307-316 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Keratinocyte ; Cadherin ; Stratification ; Epidermal morphogenesis ; Intercellular adhesion ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Classical cadherins are Ca2+-dependent homotypic intercellular adhesion molecules that play major regulatory roles in tissue morphogenesis. Human epidermis, which expresses two classical cadherins (E- and P-cadherins), undergoes continual differentiation and morphogenesis, not just during embryonic development, but throughout life. The relative roles of E- and P-cadherin in epidermal morphogenesis have been studied in human epidermal keratinocytes in culture. In these cultures, tissue morphogenesis can be initiated simply by elevation of the extracellular Ca2+ concentration, which activates the cadherins, initiates desmosome organization, and then induces reorganization of the culture from a monolayer into a multilayered, more differentiated, epithelial-like structure. By examination of cultures after several days in high Ca2+, previous data have shown that concurrent inhibition of both E- and P-cadherins nearly abrogates the Ca2+-induced stratification response; however, it has not been possible to discern from these studies whether the two cadherins have unique or redundant regulatory properties. The present study has demonstrated, via electron-microscopic analysis of cultures at an early stage in stratification, that inhibition of either of the cadherins alone does not affect the initiation of stratification, i.e. the formation of up to 2–3 cell layers. Thus, E-cadherin and P-cadherin may have similar regulatory functions with respect to the initiation of stratification. However, if stratification is to continue further to produce a tissue-like structure of 5–7 cell layers, then E-cadherin is required and P-cadherin cannot act as a substitute, presumably because of the distinct localizations of E- and P-cadherins; E-cadherin is found in all cell layers of the stratified epithelium, whereas P-cadherin is lost after the basal keratinocytes become detached from the basement membrane and assume a suprabasal position. Therefore, basal cells, which have two cadherins, can utilize either cadherin to initiate stratification, whereas superficial cells, which have only E-cadherin, are dependent on this cadherin for further stratification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050816
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    Cytokeratin 17 as an immunohistochemical marker for intramural cytotrophoblast in human first trimester uteroplacental arteries (1997)
    Springer
    Cell & tissue research 288 (1997), S. 335-343 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Uteroplacental artery ; Trophoblast invasion ; Intramural cytotrophoblast ; Cytokeratin 17 ; Placenta ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Trophoblast cells, as blastocyst-wall derivatives, are of epithelial origin and differentiate initially into syncytiotrophoblast and cytotrophoblast subpopulations. Cyto- and syncytiotrophoblasts are the two cell types present in the surface cell layers of placental villi. Cytotrophoblastic cells lie in contact with the basal lamina and are the proliferating stem cells that guarantee cytotrophoblast and syncytiotrophoblast persistence. Implantation and placenta formation are mainly based on these two cell types. Villous cytotrophoblasts are the stem cells for all extravillous trophoblast subpopulations, which exhibit strictly regulated invasiveness. One aspect of extravillous trophoblasts is that they invade maternal endometrial spiral arteries and dilate them in order to achieve sufficient fetal blood supply. During this process, trophoblast cells, which are located in the remodelled uteroplacental artery walls, are thus defined as intramural cytotrophoblasts. Trophoblast differentiation is accompanied and defined by alterations in, for example, the translation pattern for cytokeratin genes. In an immunohistochemical study, we have demonstrated that only intramural cytotrophoblasts, from all the trophoblast populations of the junctional zone, express cytokeratin 17. Furthermore, cell shape and vascular architecture indicate that, in human placenta, intra-arterial trophoblast cells reach their destination by migration through the endometrial interstitium with consecutive intravasation. Cytokeratin 17, in particular, can therefore be used as a specific immunohistochemical marker for the intramural trophoblast subpopulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050819
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    A step toward a human-robot cooperative system (1997)
    Springer
    Artificial life and robotics 1 (1997), S. 181-184 
    Details
    ISSN: 1614-7456
    Keywords: Human ; robot cooperation ; Multimedia interface ; Robot teaching method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In the near future, we will have to live with many machines such as home robots, hospital robots, and so on. User-friendly communication between humans and those machines is very important for a cooperative system utilizing their features and abilities. As an example of a human-robot cooperative system, we propose an intuitive approach to robot teaching with multimedia tools.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02471137
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    Relation of the mental foramen to teeth on the mandibles belonging to the Byzantium period (1997)
    Springer
    International journal of anthropology 12 (1997), S. 1-4 
    Details
    ISSN: 1824-3096
    Keywords: Human ; Mental foramen ; Byzantium period
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fifty mandibles belonging to the Byzantium period were studied in order to determine to racial differences about of the localization of the mental foramen according to the mandibular teeth. Mandibles of adult males without missing teeth, proximal decay and proximal attrition were used. On the right side, the most common position of the mental foramen was between the first and second lower teeth (50%), whereas on the left side, the most common position was in line with the longitudinal axis of the lower second premolar tooth (46%). Because of materials including mostly Alpine's and a few of Mediterranean subraces, two different positions of the mental foramen were determined in high similar ratios.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02447884
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  • 141
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    Face immersion increases vagal activity as assessed by heart rate variability (1997)
    Springer
    European journal of applied physiology 76 (1997), S. 394-399 
    Details
    ISSN: 1439-6327
    Keywords: Key words Diving reflex ; Heart rate fluctuation ; Breathing frequency ; Bradycardia ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We examined whether the diving reflex without breath-holding (face immersion alone) increases vagal activity, as determined by heart rate variability. A group of 15 men [mean age 20 (SD 3) years, height 172 (SD 5) cm, body mass 68 (SD 9) kg] performed 12 trials at various breathing frequencies (5, 10, 15, 20, 30 breaths · min−1 and uncontrolled breath) with or without face immersion. The R-R intervals of the ECG and gas exchange variables were recorded during the 2 min of each trial. The subjects immersed their faces in 8–10°C water while breathing through a short snorkel. The subject sat in the same position either with or without face immersion. The mean R-R interval (RRmean), standard deviations (SDRR) and coefficient of variance (CVRR) of the R-R interval were calculated from the R-R intervals during 30–120 s. The face immersion significantly increased SDRR and CVRR (P〈0.05), and increased RRmean (P〈0.05) at 20 breaths · min−1. Face immersion itself had no effect on oxygen uptake, tidal volume, end-tidal O2 and CO2 partial pressures. The diving reflex without breath-holding increased the heart rate variability, indicating that face immersion alone increases vagal activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210050267
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    Somatostatin attenuates the hyperthermia induced increase in neutrophil concentration (1997)
    Springer
    European journal of applied physiology 77 (1997), S. 149-156 
    Details
    ISSN: 1439-6327
    Keywords: Key words Hyperthermia ; Hormones ; Growth hormone ; Immunology ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study was designed to test the hypothesis that the immune changes seen during in vivo whole body hyperthermia are mediated by elevations in the plasma concentrations of either catecholamines, growth hormone or β-endorphins. Eight healthy volunteers were immersed in a hot water bath (WI; water temperature 39.5°C) for 2 h during which their rectal temperature rose to 39.5°C. In a single blind, randomized, cross-over study the stress hormone effects were blocked one at a time by administration of propranolol, somatostatin or naloxone; the results were compared to those obtained during saline infusion (control). Blood samples were collected before, at the end of 2 h of WI (body temperature 39.5°C), and 2 h later. Hormone blockade did not abolish the hyperthermia-induced recruitment of natural killer (NK) cells to the blood, and no influence was observed on the percentages or concentrations of any other subpopulations of blood mononuclear cells, except that the number of cluster designation (CD)3+ cells slightly increased after hyperthermia only in the propranolol experiment. Furthermore, the NK cell activity, both unstimulated and interferon-α or interleukin-2 stimulated, did not differ from the control situation. It is of interest, however, that somatostatin partly abolished the hyperthermia induced increase in the neutrophil number. Based on these data and previous results showing that growth hormone infusion increases the concentration of neutrophils in the blood, it is suggested that growth hormone is at least partly responsible for hyperthermia induced neutrocytosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210050313
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    Positive end expiratory pressure as a method for preventing acute mountain sickness (1997)
    Springer
    European journal of applied physiology 77 (1997), S. 32-36 
    Details
    ISSN: 1439-6327
    Keywords: Key words Acute mountain sickness ; Human ; Peep ; Prevention ; Hypoxia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to study the use of positive end expiratory pressure (PEEP) to prevent acute mountain sickness (AMS), 22 subjects were exposed randomly to 8-h hypobaric hypoxia in a hypobaric chamber (4500 m, 589 hPa, 22°C) once being administered 5-cm H2O PEEP and once without. The prevention of AMS by PEEP was evaluated by scoring AMS according to the Lake Louise system (self-report questionnaire and clinical assessment) throughout the experiment with O2 saturation (SO2) and heart rate measurements being made. Arterial blood analyses (partial pressures of arterial O2 and CO2, P aO2, P aCO2, and pH) were made at the end of the exposure. Results showed decreased AMS scores with PEEP at the end of the 8-h hypoxia [1.50 (SEM 1.32) vs 3.23 (SEM 2.07), P 〈 0.01 for self-report plus clinical assessment scores] with a lower prevalence (23% vs 55%, P 〈 0.01). The SO2, P aO2, P aCO2 and HCO3 − did not change significantly. However, a smaller increase in arterial pH [7.47 (SEM 0.02) vs 7.50 (SEM 0.02), P 〈 0.05] was observed with PEEP, attesting a lesser alkalosis. Moreover, heart rate increased with PEEP (P 〈 0.05). In conclusion, this study would suggest that a 5-cm H2O PEEP may help decrease AMS scores at the end of an 8-h exposure to hypoxia in a hypobaric chamber. Such a method could be used to prevent AMS in such experimental conditions without adverse effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210050296
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  • 144
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    Influence of long-latency reflex modulation on the performance of quick adjustment movements (1997)
    Springer
    European journal of applied physiology 76 (1997), S. 328-334 
    Details
    ISSN: 1439-6327
    Keywords: Key words Muscle stretch ; Long-latency reflex ; Adjustment movement ; Motor control ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of long-latency reflex modulation on the performance of a quick adjustment movement following a muscle stretch was studied in 26 healthy male subjects. When the subjects felt a sudden angle displacement in the direction of a wrist extension they were required to make an adjustment movement by moving a handlebar, held in the hand, to align with a target position as quickly and as accurately as possible. The index of performance (adjustment time) was the time taken to move the handle to the target position from stretch onset. A DC torque motor was used to evoke electromyographic (EMG) reflex responses on a wrist flexor. Averaging of the rectified EMG, recorded from surface electrodes placed over the flexor, showed short- and long-latency reflexes (M1 and M2 components). For all subjects, the amplitudes of the reflex components decreased during the adjustment movement because the target position for this study was fixed to the extension side of the wrist joint. The decrease in the M2 component, which is considered to be a transcortical reflex, was significantly larger than the decrease in the M1 component, which is spinal reflex. The main finding was of a positive correlation between the length of adjustment time and the degree of reduction of M1 and M2 with the adjustment movement (r = 0.602 for M1, P 〈 0.01; r = 0.850 for M2, P 〈 0.001). Moreover, there were correlations between the consistency of the voluntary response onset and the degree of M2 decrease (r = 0.577, P 〈 0.01), and between the consistency of the voluntary response onset and the length of the adjustment time (r = 0.603, P 〈 0.01). Therefore, we have concluded that the subjects who were able to perform adjustment movements within a short time could modulate the long-latency reflex of the muscle involved in such movements in order to make the function of their voluntary muscle activity more effective, and thus were able to respond appropriately.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210050256
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    Biomechanik von Femurverriegelungsmarknägeln im Knochen-Implantat-Verbund (1997)
    Springer
    Langenbeck's archives of surgery 382 (1997), S. 167-172 
    Details
    ISSN: 1435-2451
    Keywords: Key words Biomechanics ; Fracture-fixation-intramedullary ; Femoral fractures-diaphyseal ; Unreamed ; Cadaver study ; Human ; Schlüsselwörter Biomechanik ; Intramedulläre Frakturfixation ; Femorale Diaphysenfraktur ; Unaufge-bohrt ; Studie an menschlichen Leichen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Ziel der Studie war die vergleichende Untersuchung verschiedener Femurverriegelungsnägel auf die Primärstabilität im Knochen-Implantat Verbund (KIV). Dabei wurden die folgenden Implantate in einer Modellosteosynthese getestet: AO-Universal-Femur-nagel (AOU) 11 mm, AO unaufgebohrter Femurnagel Stahl 9 mm, Verriegelung mit 3,2–3,9-mm-Bolzen (SUFN3,9), SUFN 9 mm, mit 4,3–4,9-mm-Bolzen (SUFN4,9), AO unaufgebohrter Femurnagel Titan (12TUFN) 12 mm, mit 4,3–4,9-mm-Bolzen, TUFN 9 mm, Verriegelung mit 4,3–4,9-mm-Bolzen (9TUFN). Die Prüfungen wurden mit einer Universalprüfmaschine an 40 humanen, gepaarten, kältekonservierten Kadaverfemora durchgeführt. Jeder einzelne Knochen wurde zunächst im intakten Zustand geprüft, dann wurde die Osteotomie durchgeführt und das jeweilige Implantat eingesetzt. Ausgewertet wurde die relative Steifigkeit. Es zeigte sich eine signifikant höhere Torsionssteifigkeit der nicht soliden ungeschlitzten Femurnägel im Vergleich zu dem geschlitzten AOU. Die Biegesteifigkeit des KIV des TUFN mit 12 mm Durchmesser war signifikant höher als die Biegesteifigkeit des KIV der anderen Implantate. Bei der axialen Belastung zeigte der KIV des SUFN4,9 eine signifikant höhere Steifigkeit als der KIV des TUFN. Die Steifigkeitsunterschiede zwischen den verschiedenen KIV waren bei der axialen Belastung und Biegebelastung relativ geringer als bei der Torsion. Für die Torsionssteifigkeit ist das Nagelprofil (±Schlitz) entscheidender Parameter. Zwischen den soliden Implantaten zeigten sich ebenfalls signifikante Unterschiede für die Biegung und axiale Belastung.
    Notes: Abstract Today there is a variety of different interlocking intramedullary nail designs available for the femur – each designed with a different approach to achieve stability for fracture fixation. We compared different nail types in the bone-implant complex (BIC) of four unreamed solid nails and a slotted, reamed nail to see if there are major differences in stiffness for axial load, bending and torsion. We simulated comminuted mid-shaft fractures by a 2 cm defect osteotomy in paired human cadaver femora. Each bone was tested intact in a Universal testing machine. The results were recorded, osteotomy and osteosynthesis were performed, and the BIC was tested. Relative stiffness was calculated for each individual bone. For P-values less than 0.01 (`least significance difference test') the difference between groups was considered to be significant. In torque testing the unslotted solid nails showed significantly more stiffness (0.6–1.8 Nm/°) compared to the slotted nail (0.2 Nm/°). Compared to intact bone (6.9 Nm/°), both groups of nails were significantly less stiff (relative stiffness 2–20%). In axial load and bending testing, the large-diameter unreamed nail showed greater higher stiffness (32–68%). This study shows that stiffness of the BIC in interlocking femoral nails is more dependent on nail profile than on the press-fit of nails in the medullary canal. For torque stiffness the absence of a slot is of special importance. According to our study, all of the unslotted nails tested give adequate stability for fracture fixation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008037
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    Naphthopyranquinone Antibiotics: Novel enantioselective syntheses of frenolicin B and some of its stereoisomers (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 43-58 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new enantioselective syntheses of the naphthopyranquinone antibiotic frenolicin B (1), of its enantiomer 2, and of its diastereoisomers 3 and 4 were accomplished using two different routes from optically active β-Hydroxy esters (R)- and (S)-11 and 18. β-Hydroxy esters (R)- and (S)-11 were prepared stereoselectively from optically active sulfenylacetates (S)- and (R)-10, respectively (Scheme 2, Method A). Alternatively, compound 18 was obtained in excellent yield by enantioselective hydrogenation of the corresponding β-keto ester 17, using a chiral ruthenium-complex catalyst (Scheme 3, Method B). Subsequently, compounds (S)-11 and 18 were transformed into frenolicin B (1). In analogy, Stereoisomers 2-4 were prepared from (S)- and (R)-11 in good yields.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800104
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    Oligonucleotides Containing Consecutive 2′-Deoxyisoguanosine Residues: Synthesis, duplexes with parallel chain orientation, and aggregation (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 73-85 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2′-deoxyisoguanosine phosphonates 3a and 4a and the phosphoramidites 3b and 4b were prepared as building blocks for solid-phase oligonucleotide synthesis. The diphenylcarbamoyl (dpc) residue was introduced as 2-oxo protecting group which stabilizes the N-glycosylic bond against hydrolysis and prevents the molecule from side reactions. The dpc-protected building blocks 4a, b were employed in solid-phase synthesis and were found to be much more efficient than the unprotected compounds 3a, b. Oligonucleotides with alternating (11) or consecutive isoguanine residues (13-15) were synthesized. They form duplexes with parallel chain orientation. The aggregate d(T4-iG4-T4) (15) containing four consecutive 2′-deoxyisoguanosine is shown to be a tetramer similar to that of d(T4-G4-T4).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800107
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  • 148
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    Synthesis and Odor of Chiral Partial Structures of Khusimone. Part 1Dedicated with best personal wishes to Prof. Dr, W. Fleischhacker on the occasion of his 65th birthday (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 139-145 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Khusimone (1), one of the main odor-donating compounds of vetiver oil is subject of the following study on structure/odor relationship. The omittance of the ethano bridge of the tricyclic khusimone leads to a bicyclic system. The stereoselective approach to this degraded structure is described, and the olfactory properties are studied. The key step of the synthesis of the hydrindane nucleus is based on a highly diastereoselective conjugate addition to a chiral oxo-cyclopentene-2-carboxylate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800114
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    Nucleotides. Part LPart IL:[1]. Aglycone protection by the (2-dansylethoxy)carbonyl (= {2-{[5-(dimethylamino)naphthalen-l-yl]sulfonyl}ethoxy}carbonyl; dnseoc) group a new variation in oligodeoxyribonucleotide synthesis (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 200-212 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The (2-dansylethoxy)carbonyl (= {2-{[5-(dimethylamino)naphthalen-l-yl]sulfonyl}ethoxy}carbonyl; dnseoc) group was employed for protection of the amino functions of the aglycone residues. The lactam function of 2′-deoxyguanosine was on the one hand unprotected and on the other hand alkylated at O6 of the aglycone with the 2-(4-nitrophenyl)ethyl (npe) and 2-(phenylsulfonyl)ethyl (pse) group, respectively. The syntheses of monomeric building blocks, both phosphoramidites and nucleoside- functionalized supports, are described for the three common 2′-deoxynucleosides (2′-deoxycytidine, 2′-deoxyadenosine, 2′-deoxyguanosine). As kinetic studies with the tritylated nucleosides showed, the dnseoc group is more labile towards DBU cleavage than the corresponding 2-(4-nitrophenyl)ethyl-(npe) and [2-(4-nitrophenyl)ethoxy]carbonyl(npeoc)-protected analogues (see Table 2). These results were confirmed by the very fast deprotection rate of the dnseoc groups at some oligonucleotides.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800118
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    The Absolute Configuration of 3-Methylpyrrolidine Alkaloids from Poison Glands of Ants Leptothoracini (Myrmicinae) (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 267-272 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The absolute configuration of 3-methylpyrrolidine alkaloids isolated from the poison gland of ants Leptothoracini was determined as (3R). The enantiomeric separation by chiral gas chromatography and unambiguous structural assignment of the target compounds are described.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19970800124
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    Mitteilungen (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 317-318 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800127
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    New Heptalenes Substituted with Extended π-Systems (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 253-266 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of π-substituted heptalenecarboxylates or -dicarboxylates, starting with the easily available dimethyl 9-isopropyl-1, 6-dimethylheptalene-4, 5-dicarboxylate (2b), are described. Treatment of 2b with t-BuOK and C2Cl6 at -78° leads to the chemoselective introduction of a Cl substituent in Me-C(1) (see 5b in Scheme 1). Formation of the corresponding triphenylphosphonium salt 7b via the iodide 6b (Scheme 2) allowed a Wittig reaction with cinnamaldehyde in the two-phase system CH2Cl2/2N NaOH. Transformation of the 4, 5-dicar-boxylate of 2b into the corresponding pseudo-ester 10b allowed the selective reduction of the carbonyl function at C(4) with DIBAH to yield the corresponding 4-carbaldehyde 11b (Scheme 3). Wittig reaction of 11b with (benzyl) triphenylphosphonium bromide led to the introduction of the 4-phenylbuta-1, 3-dienyl substituent at C(4). The combination of both Wittig reactions led to the synthesis of the 1, 4-bis(4-phenylbuta-1, 3-dienyl)-substituted heptalene-5-carboxylate (all-E)-17b (Scheme 5). In a similar manner, by applying a Horner-Wadsworth-Emmons reaction, followed by the Wittig reaction, the donor-acceptor substituted heptalene-5-carboxylate (E;E)-22b was synthesized (Scheme7). Most of these new heptalenes are in solution, at room temperature, in thermal equilibrium with their double-bond shifted (DBS) isomers. In the case of (all-E)-17b and (E;E)-22b, irradiation of the thermal equilibrium mixture with light of λ -(439 ± 10) nm led to a strong preponderance ( 〉 90%) of the DBS isomers 17a and (E;E)-22a, respectively (Schemes 6 and 7). Heating of the photo-mixtures at 40° re-established quickly the thermal equilibrium mixtures. Heptalenes-carboxylates (all-E)-17a and (E;E)-22a which represent the off-state of a 1,4-conjugative switch (CS) system show typical heptalene UV/VIS spectra with a bathochromically shifted heptalene band III and comparably weak heptalene bands II and I which appear only as shoulders (Figs. 4 and 5). In contrast, the DBS isomers (all-E)-17b and (all-E)-22b, equivalent to the on-state of a 1,4-CS system, exhibit extremely intense heptalene bands I and, possibly, II which appear as a broad absorption band at 440 and 445 nm, respectively, thus indicating that the CSs (all-E)-17a⇌(all-E)-17b and (E;E)-22a⇌(E;E)-22b are perfectly working.
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    URL: http://dx.doi.org/10.1002/hlca.19970800123
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    Konfigurations- und konformationsisomere antiaromatische [28]Tetraoxaporphyrinoide(4.2.4.2) und aromatische [26]Tetraoxaporphyrin(4.2.4.2)-dikationen. Eine neue Form molekularer Dynamik in makrocyclischen Systemen (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 14-42 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Configurational and Conformational Isomeric Antiaromatic [28]Tetraoxaporphyrinoids(4.2.4.2) and Aromatic [26]Tetraoxaporphyrin(4.2.4.2) Dications. A New Type of Molecular Dynamics in Macrocyclic SystemsThe [28]tetraoxaporphyrinoids(4.2.4.2) 6 are synthesized by cyclizing Wittig reaction of (E, E)-5, 5′-(buta-1, 3-diene-1, 4-diyl)bis[furan-2-carbaldehyde] (8) with (E, E)-{(buta-1, 3-diene-diyl)bis[(furan-5, 2-diyl)methylene]}bis-[triphenylphosphonium] dibromide (9) and 3, 3′-{[(E)-ethene-1, 2-diyl]bis(furan-5, 2-diyl)}bis[(E)-prop-2-enal] (22) with (E)-{(ethene-1, 2-diyl)bis[(furan-5.2- diy)methylene]}bis[triphenylphosphonium] dibromide (23). An alternative path to get 6 is the McMurry condensation of 8. Four different configurational isomers of 6 could be isolated and characterized by 1H-NMR spectroscopy. The (Z, EE, Z, EE)-isomer 6a is the first macrocyclic system where the inner and outer protons of the (E, E)-dienediyl bridges exchange by rotation around the adjacent single bonds. In the (Z, EE, E, EE)-isomer 6b, the (E)-ethenediyl bridge is rotationally active, while in the (E, ZE, E, EZ)-isomer 6c and in the (E, EZ, E, EZ)-isomer 6e, the rotation of both (E)-ethenediyl bridges is observed. When in the dynamic systems the rotation of the active (E)-double bonds at temperatures T 〈 -90° is frozen, all configurational isomers of 6 appear to be antiaromatic and paratropic. The oxidation of the [28]tetraoxaporphyrinoids 6c and 6e with DDQ yields the aromatic, diatropic [26]tetraoxaporphyrin(4.2.4.2) dications 21e/21e′ both with (E, EZ, E, EZ)-configuration but different fixed conformations. (Z, EE, Z, EE)-Isomer 6a is oxidized to give the (Z, EE, Z, EE)-dication 21a, while the oxidation of 6b yields a mixture of 21a and 21e/21e′. The standard formation enthalpies of the obtained and expected [28]tetraoxaporphyrinoids 6 and [26]tetraoxaporphyrin dications 21 have been calculated with the AM1 method, showing good accordance with the experimental results.
    Additional Material: 15 Ill.
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    Diastereoselective Synthesis of Cyclododeca-1,6-diallenes ( = cyclododeca-l,2,6,7-tetraenes) (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 414-420 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of substituted cyclododeca-1,6-diallenes.( = cyclododeca-1,2,6,7-tetraenes) from cyclododeca-5,11-diyne-1,4-diols is described (Schemes 1 and 3). The ca. 1:1 mixtures of the stereoisomers of the cyclododeca-1,6-diallenes were formed in high yields from the ca. 1:1 diastereoisomer mixtures of the 1,4-disubstituted cyclododeca-5,11-diynes by reactions with Me2CuLi or t-BuMgCl/CuII. In mechanistically relevant experiments with the pure diastereoisomers of 1,4-dimethylcyclododeca-5,11-diyne-1,4-diol, it is demonstrated that the configuration is conserved in these reactions. The first synthesis of a 1-substituted cyclododeca-2,8-diyne bearing only one propargylic leaving group gives access to a mixed 12-membered allen-yne (Scheme 5).
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    Lipophilicity Behavior of Model and Medicinal Compounds containing a suilfide, sulfoxide, or sulfone moiety (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 449-462 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This study was designed to unravel lipophilicity changes associated with the oxidation state of the S-atom in model compounds, drugs, and metabolites, special attention being given both to intermolecular and intramolecular effects. The methods used were experimental (potentiometry, CPC, and shake-flask techniques to measure lipophilicity, 13C-NMR spectroscopy to investigate tautomeric equilibria) and computational (quenched molecular dynamics and molecular lipophilicity potential). Simple, monofunctional model compounds were used to assess intermolecular forces, as revealed by the Δlog Poct-alk and Δlog Poct-chf parameters. Drugs and their metabolites proved to be good probes to study intramolecular effects in both neutral and anionic forms, as revealed by the difference between calculated and experimental log Poct values (the diff(log Pexp-calc) parameter). Sulindac and its metabolites showed a normal partitioning behavior, whereas the lipophilicity of sulfmpyrazone and its metabolites' was markedly affected by tautomeric and conformational equilibria.
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    URL: http://dx.doi.org/10.1002/hlca.19970800210
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    Methanofullerene Molecular Scaffolding: Towards C60-substituted poly(triacetylenes) and expanded radialenes, preparation of a C60-C70 hybrid derivative, and a novel macrocyclization reaction (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 293-316 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of (E)-hex-3-ene-l, 5-diynes and 3-methylidenepenta-1, 4-diynes with pendant methano[60]-fullerene moieties as precursors to C60-substituted poly(triacetylenes) (PTAs, Fig. 1) and expanded radialenes (Fig. 2) is described. The Bingel reaction of diethyl (E)-2, 3-dialkynylbut-2-ene-1, 4-diyl bis(2-bromopropane-dioates) 5 and 6 with two C60 molecules (Scheme 2) afforded the monomeric, silyl-protected PTA precursors 9 and 10 which, however, could not be effectively desilylated (Scheme 4). Also formed during the synthesis of 9 and 10, as well as during the reaction of C60 with thedesilylated analogue 16 (Scheme 5), were the macrocyclic products 11, 12, and 17, respectively, resulting from double Bingel addition to one C-sphere. Rigorous analysis revealed that this novel macrocyclization reaction proceeds with complete regio- and diastereoselectivity. The second approach to a suitable PTA monomer attempted N, N′-dicyclohexylcarbodiimide(DCC)-mediated esterification of (E)-2, 3-diethynylbut-2-ene-l, 4-diol (18, Scheme 6) with mono-esterified methanofullerene-dicarboxylic acid 23; however, this synthesis yielded only the corresponding decarboxylated methanofullerene-carboxylic ester 27 (Scheme 7). To prevent decarboxylation, a spacer was inserted between the reacting carboxylic-acid moiety and the methane C-atom in carboxymethyl ethyl 1, 2-methano[60]fullerene-61, 61-dicarboxylate (28, Scheme 8), and DCC-mediated esterification with diol 18 afforded PTA monomer 32 in good yield. The formation of a suitable monomeric precursor 38 to C60-substituted expanded radialenes was achieved in 5 steps starting from dihydroxyacetone (Schemes 9 and 10), with the final step consisting of the DCC-mediated esterification of 28 with 2-[1-ethynyl(prop-2-ynylidene)]propane-1, 3-diol (33). The first mixed C60-C70 fullerene derivative 49, consisting of two methano[60]fullerenes attached to a methano[70]fullerene, was also prepared and fully characterized (Scheme 13). The Cs-symmetrical hybrid compound was obtained by DCC-mediated esterification of bis[2-(2-hydroxy-ethoxy)ethyl] 1, 2-methano[70]fullerene-71, 71-dicarboxylate (46) with an excess of the C60-carboxylic acid 28. The presence of two different fullerenes in the same molecule was reflected by its UV/VIS spectrum, which displayed the characteristic absorption bands of both the C70 and C60 mono-adducts, but at the same time indicated no electronic interaction between the different fullerene moieties. Cyclic voltammetry showed two reversible reduction steps for 49, and comparison with the corresponding C70 and C60 mono-adducts 46 and 30 indicated that the three fullerenes in the composite fullerene compound behave as independent redox centers.
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    Bis- through Tetrakis-Adducts of C60 by Reversible Tether-Directed Remote Functionalization and systematic investigation of the changes in fullerene properties as a function of degree, pattern, and nature of functionalization (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 343-371 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By the tether-directed remote functionalization method, a series of bis- to hexakis-adducts of C60, i.e., 1-7 (Fig. 1), had previously been prepared with high regioselectivity. An efficient method for the removal of the tether-reactive-group conjugate was now developed and its utility demonstrated in the regioselective synthesis of bis- to tetrakis(methano)fullerenes ( = di- to tetracyclopropafullerenes-C60-Ih) 9-11 starting from 4, 5, and 7, respectively (Schemes 2, 4, and 5). This versatile protocol consists of a 1O2 ene reaction with the two cyclohexene rings in the starting materials, reduction of the formed mixture of isomeric allylic hydroperoxides to the corresponding alcohols, acid-promoted elimination of H2O to cyclohexa-1,3-dienes, Diels-Alder addition of dimethyl acetylenedicarboxylate, retro-Diels-Alder addition, and, ultimately, transesterification. In the series 9-11, all methano moieties are attached along an equatorial belt of the fullerene. Starting from C2v-symmetrical tetrakis-adduct 15, transesterification with dodecan-1-ol or octan-1-ol yielded the octaesters 16 and 17, respectively, as noncrystalline fullerene derivatives (Scheme 3). The X-ray crystal structure of a CHCl3 solvate of 11 (Fig. 3) showed that the residual conjugated π-chromophore of the C-sphere is reduced to two tetrabenzopyracylene substructures connected by four biphenyl-type bonds (Fig. 5). In the eight six-membered rings surrounding the two pyracylene (= cyclopent[fg]acenaphthylene) moieties, 6-6 and 6-5 bond-length alteration (0.05 Å) was reduced by ca. 0.01 Å as compared to the free C60 skeleton (0.06 Å) (Fig. 4). The crystal packing (Fig. 6) revealed short contacts between Cl-atoms of the solvent molecule and sp2- and sp3-C-atoms of the C-sphere, as well as short contacts between Cl-atoms and O-atoms of the EtOOC groups attached to the methano moieties of 11. The physical properties and chemical reactivity of compounds 1-11 were comprehensively investigated as a function of degree and pattern of addition and the nature of the addends. Methods applied to this study were UV/VIS (Figs. 7-11), IR, and NMR spectroscopy (Table 2), cyclic (CV) and steady-state (SSV) voltammetry (Table 1), calculations of the energies of the lowest uunoccupied mmolecular orbitals (LUMOs) and electron affinities (Figs. 12 and 13), and evaluation of chemical reactivity in competition experiments. It was found that the properties of the fullerene derivatives were not only affected by the degree and pattern of addition but also, in a remarkable way, by the nature of the addends (methano vs. but-2-ene-1, 4-diyl) anellated to the C-sphere. Attachment of multiple thano moieties along an equatorial belt as in the series 8-11 induces only a small perturbation of the original fullerene π-chromophore. In general, with increasing attenuation of the conjugated fullerene π-chromophore, the optical (HOMO-LUMO) gap in the UV/VIS spectrum is shifted to higher energy, the number of reversible one-electron reductions decreases, and the first reduction potential becomes increasingly negative, the computed LUMO energy increases and the electron affinity decreases, and the reactivity of the fullerene towards nucleophiles and carbenes and as dienophile in cycloadditions decreases.
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    Variants of Solid-State and Solution Structures of (η3-Allyl)- {2-[2′-(diphenylphosphino)phenyl]-4,5-dihydrooxazole-P,N}palladium(II) hexafluorophosphates and tetraphenylborates (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 463-471 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crystal and solution structures of the enantiomerically pure and the racemic pairs of (η3-allyl) {2-[2′-(diphenylphosphino)phenyl]-4,5-dihydro-4-phenyloxazole}palladium(II) hexafluorophosphates (1, and rac-1, resp.) and tetraphenylborates (2, and rac-2, resp.) as well as (η3-allyl){2-[2′-(diphenylphosphino)phenyl]-4,5-dihydro-4-isopropyloxazole}palladium(II) tetraphenylborate (3) were characterized by X-ray crystallography and 1H-NMR spectroscopy. In the solid state, rac-1 and rac-2 proved to be disordered with both diastereoisomeric complexes in the crystal. The complexes 2 and 3 exist only in the ‘exo’ form. The X-ray structures show that the [PdII(η3-allyl)] moiety may adopt different configurations between a nearly symmetrical three-electron PdII(π3-allyl) system and an asymmetrical allyl group with a η1- and a η2-bonding to the metal center. The [PdII(η3-allyl)] system of rac-1 and of ‘endo’ rac-2 is closer to the former, and that of 2, ‘exo’-rac-2, and 3 closer to the later geometry. The 1H-NMR spectra of the hexafluorophosphates 1 and rac-1 show two sets of signals of the allylic protons in an ‘exo’/‘endo’ ratio of 2:3. The tetraphenylborates 2, rac-2, and 3 give only one set of broad signals of the allylic protons.
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    Oligosaccharide Analogues of Polysaccharides. Part 12Part 11: [1]. Synthesis of ‘acetyleno-saccharide’-derived cyclodextrin analoguesDedicated to Prof., Dr. Dieter Seebach on the occasion of his 60th birthday (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1027-1052 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ‘Acetyleno-oligosaccharides’ in which two terminal ethynyl substituents enclose an angle (significantly) below 180° are building blocks for the preparation of cyclodextrin analogues. This is illustrated by the preparation of a cyclotrimer and a cyclotetramer; the C3-symmetrical cyclotrimer 18 (Scheme 1) was synthesized in 13 steps (7.7%) and the C4-symmetrical cyclotetramer 51 (Scheme 3) in 14 steps (4.3%) from the known dialkyne 21. The solubilities of 18 and 51 in H2O were determined by gravimetry; a saturated solution is 130 mM in the trimer 18 and 12.8 mM in the tetramer 51. The dependence of the optical rotation of 18 and 51 in H2O on the concentration, and the concentration dependence of the 1H-NMR chemical shift of the signals of the 1CH groups of 51 (D2O) suggest that there is no significant self-association of 18 and 51.
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    URL: http://dx.doi.org/10.1002/hlca.19970800403
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    Synthesis of Chiral Bicyclic Bis-lactam Components for the controlled self-assembly of hydrogen-bonded arrays (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 856-875 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chiral biyclic bis-lactams of structures 3 and 4 were synthesized from the key intermediate 2′b, the N,N′-bis(4-methoxybenzyl) derivative of 2 (X = MeO) (Scheme 6). The synthesis of this intermediate involved two key steps: (1) a double condensation of glyoxylic acid/anisamide (= oxoacetic acid/4-methoxybenzamide) adduct 11c with veratrole (1,2-dimethoxybenzene; 10) allowed the introduction of two glycine units at the 4,5-positions of the veratrole ring to give 18c (Schemes 3 and 4); (2) in order to circumvent the hydrolysis of 4-methoxybenzoyl protective groups which proved to be unfeasible, these groups were transformed into 4-methoxybenzyl groups through a sequence involving thiocarbonylation followed by reduction (Scheme 5). Thereafter, the double intramolecular cyclization of the resulting diamino diester 22c proceeded easily to afford 2′b. This intermediate may be transformed via the tetrol 2′g or the diol 2′h into the N-protected derivatives of 2 (X = OR) and of 3 (X = OCOR). Cleavage of the 4-alkuxybenzyl groups was achieved by ceric ammonium nitrate. However, when the aromatic ring bore ether functions (N-protected 2), this normal reaction was accompanied by the oxidative ring cleavage to give the diene-diester structure 4 (Schemes 5 and 6).
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    URL: http://dx.doi.org/10.1002/hlca.19970800320
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    Metal Complexes with Macrocyclic Ligands. Part XLIVPart XLIII:[1] Kinetics of the Cu2+ incorporation into a macrocyclic ligand conjugated to proteins: Model studies for the d‘post-labeling’ technique (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 934-947 
    Details
    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.
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    URL: http://dx.doi.org/10.1002/hlca.19970800325
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    Synthesis of Medium- and Large-Ring Compounds Initiated by Photochemical Decarboxylation of ω-PhthalimidoalkanoatesDedicated to Prof. Waldemar Adam and Prof. Dieter Seebach on the occasions of their 60th birthdays on July 26th and October 31st 1997, respectively (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 912-933 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a variety of hydroxylactams from ω-phthalimidoalkanoates using a triplet-sensitized photodecarboxylation reaction initiated by intramolecular photo electron transfer is described. Ring sizes available by this method span from 4 (benzazepine-1,5-dione 7) to 26 (cyclodipeptide 26e). Ground-state template formation is proposed as the explanation for the high efficiency of this reaction and for the decrease in reactivity in the presence of organic bases instead of metal carbonates. The crucial step in this macrocyclization reaction seems to be the protonation of the intermediary ketyl radials (Scheme 4). Spacer groups investigated were alkyl chains (C3-C11: 5c-h, 11a, 12), ether (16, 18), ester (20, 22), and amide (26a-f) linkages. Within the detection limits, no dimeric (= decarboxylative coupling) products were observed, indicating the high preference for intra-vs. intermolecular photoelectron transfer. The C,C radical combination step proceeds with low stereoselectivity (cf, products 11 and 12) in contrast to comparable singlet reactions. Except for the lactones 22, all products were stable under the photolysis conditions. Prolonged irradiation of 22 led to the formation of the spiro compounds 23, probably via an intermediary acyliminium betaine (Scheme 8). One serious limitation of the decarboxylative macrocyclization is its incompatibility with the glycine spacer (as in 27a and 27b), probably the consequence of a strong intramolecular H-bond (Scheme 10).
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    URL: http://dx.doi.org/10.1002/hlca.19970800324
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  • 163
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    Mitteilungen (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 988-988 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800330
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  • 164
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    Synthesis of a Novel Tricyclic Dipeptide Template and Its Incorporation into a Cyclic Peptide Mimetic Containing an NPNA Motif (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1513-1527 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel tricyclic dipeptide template, formally derived by coupling (2S,4S)-4-aminoproline (Pro(NH2)) and (S)-2-(carboxymethyl)proline (Pro(CH2COOH)) as a diketopiperazine, has been synthesized in a form suitable for solid-phase peptide synthesis using Fmoc chemistry. This template was incorporated into the cyclic molecule cyclo(-Ala1-Asn2-Pro3-Asn4-Ala5-Ala6-Temp-) (Temp = template), whose conformation in H2O was studied by NMR methods. Average solution structures derived by restrained simulated annealing point to a highly populated βI-turn within the Asn-Pro-Asn-Ala motif and also indicate which conformations are likely to be preferred by the template.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19970800514
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  • 165
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    Aza-Claisen Rearrangement: Synthesis of 5′-branched 5′-aminothymidinesDedicated with best personal wishes of D. B. to Professor Oskar Jeger on the occasion of his 80th birthday (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1589-1606 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses of both diastereoisomers of 5′-ethyl-substituted thymidine dimers, the (5′R)- and (5′S)-configurated 33a and 33b respectively, in which the natural phosphodiester linkage is replaced by an amide group (C(3′)-CH2CONH-CH(5′)(Et)), arc described. Their fully protected derivatives 35a and 35b, respectively, are suitable for incorporation into antisense oligonucleotides. Unexpectedly, an attempted PdII-catalysed aza-Claisen rearrangement of trichloroacetimidate 7 provided the diastereoisomerically pure cyclopropane derivative 17, whose structure was confirmed by X-ray analysis.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19970800517
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  • 166
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    Neue Wege zu Pentalen-Vorstufen17. Mitteilung über Kupplungsreaktionen 16. Mitteilung (Kurzmitteilung): [1] (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1627-1638 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Pathways to Precursors of PentalenePentalene dimers 2 and 3 are easily available in moderate yields by CuCl2-induced oxidative coupling of dilithium-pentalenediide (5) (Scheme 1). On the other hand, NBS bromination of 1,5-dihydropentalene (4) or of 1,2-dihydropentalene (8) gives unstable 1-bromo-1,2-dihydropentalene (9), while subsequent in-situ elimination with Et3N exclusively gives syn-cis-pentalene dimer 2 in moderate yields (Scheme 3). NMR-Spectroscopic evidence for compounds 2, 3, and 9 is presented, and mechanistic alternatives for the formation of pentalene dimers 2 and 3 are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800520
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  • 167
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    Masthead (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997) 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800601
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  • 168
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    Iridoid Glucosides with Free Radical Scavenging Properties from Fagraea blumei (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1144-1152 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four new iridoid glucosides 1-4, named blumeosides A-D, were isolated from the methanolic stem-bark extract of Fagraea blumei G. DON. (Loganiaceae). They were accompanied by the benzyl-alcohol derivative di-O-methylcrenatin (5) and the flavone C-glucoside swertisin (6). The structures of 1-4 were established by spectroscopic methods, including FAB-MS, and 1H- and 13C-NMR, and by alkaline hydrolysis. Blumeosides A (1) and C (3) are 10-O-(2,5-dihydroxytercphthalo) adoxosidic acid and 10-O-(2-hydroxyterephthalo)adoxosidic acid, respectively. In blumeosides B (4) and D (2), both carboxylic groups of the terephthalic-acid moiety are esterified by adoxosidic-acid units, Blumeosides A-D (1-4) inhibited bleaching of crocin induced by alkoxyl radicals. Blumeosides A (1) and D (2) also demonstrated scavenging properties towards the 2,2-diphenyl-1-picryl-hvdrazvl (CDPPH) radical in TLC autographic and spectrophotometric assays.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800411
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  • 169
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    Reformulating the Kinetic Approach of Column Chromatography for a Single Component (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1176-1182 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetic model of column chromatography is revisited to explicitly show that this approach yields, when neglecting axial dispersion, a rather simple analytical expression depending only on two dimensionless parameters, namely a dimensionless kinetic retention parameter and a dimensionless time parameter. An expression for the time corresponding to the maximum of the peak is also proposed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800415
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  • 170
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    Synthesis of Unnatural Lipohilic N-(9H-Fluoren-9-ylmethoxy)carbonyl-Substituted α-Amino Acids and Their Incorporation into Cyclic RGD-Peptides: A structure-activity studyDedicated to Peter Welzel on the occasion of his 60th birthday (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1280-1300 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The αv/β3 integrin is implicated in human tumor metastasis and angiogenesis. It has been shown that structures of the sequence cyclo(-Arg1-Gly2-Asp3-D-Phe4-Xaa5-) (I) and cyclo(-Arg1-Gly2-Asp3-Phe4-D-Xaa5-) (II) bind with high affinity and the latter with high selectivity to this receptor. The residues Xaa and D-Xaa accept a broad variety of amino acids. Here, we report on the synthesis, activities, and conformational analysis of cyclic Arg-Gly-Asp (RGD) peptides containing liophilic amino acids Xaa or D-Xaa in position 5. For I, these were (2S)-2-aminohexadecanoic acid (Ahd) and N′-hexadecylglycine (Hd-Gly) and in II, D-Ahd and Hd-Gly, and, for control purposes, Ahd were incorporated (Fig. 1). The enantiomerically pure a-amino acids were obtained by non-enantioselective synthesis and subsequent enzymatic separation of isomers using acylase I (Scheme). Hd-Gly was prepared in a modified procedure according to Stewart from ethyl bromoacetate and hexadecylamine (Scheme). The synthesis and physicochemical properties of the corresponding (9H-fluoren-9-ylmethoxy)carbonyl (Fmoc) derivatives, compatible with solid-phase peptide synthesis, are described. Structure elucidation by NMR reveals that the lipid modification has no significant impact on the template structures when incorporated into them. For peptides I with Xaa = Ahd or Hd-Gly (1 or 2), a βII′/γ-turn-like arrangement with D-Phe in i+1 position of the β-turn is found. Peptides II with D-Xaa = D-Ahd or Hd-Gly (3 or 4) exhibit a βII′/γ-turn conformation with Gly in i+1 position of the β-turn, whereas II with Ahd instead of D-Xaa, i.e., lacking a D-amino acid in position 4 or 5 (5). adopts no defined conformation. However, in assays of receptor specificity employing human αvv/β3 integrin, the compounds exhibit IC50 values ranging from nanomolar to less than millimolar. These results indicate that although the arrangement of the pharmacophoric groups is preserved in the target compounds, the biological activity is highly dependent on spatial requirements of the lipid anchor in the receptor binding pocket. Obviously, only certain positions do not affect the binding.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800423
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  • 171
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    Cyclic Heptapeptides Axinastatin 2, 3, and 4: Conformational analysis and evaluation of the biological potentialDedicated to Ernst Bayer on the occasion of his 70th birthday (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1338-1354 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational analysis of naturally occurring cytostatic cyclic heptapeptides axinastatin 2, 3, and 4 was carried out by two-dimensional NMR spectroscopy in combination with distance-geometry (DG) and molecular-dynamics (MD) calculations in explicit solvents. The synthesized secondary metabolites were examined in (D6)DMSO. Axinastatin 2 was also investigated in CD3OH. In all structures, Pro2 is in the i + 1 position of a βI turn and Pro6 occupies the i + 2 position of a βVIa turn about the cis amide bond between residue 5 and Pro6. In all peptides, a bifurcated H-bond occurs between residue 4 CO and the amide protons of residue 1 and 7. For axinastatin 2 and 3, an Asn Ig turn was found about Asn1 and Pro2. We compared these structures with conformations of cyclic heptapeptides obtained by X-ray and NMR studies. A β-bulge motif with two β turns and one bifurcated H-bond is found as the dominating backbone conformation of cyclic all-L-heptapeptides. Axinastatin 2, 3, and 4 can be characterized by six trans and one cis amide bond resulting in a β/βVI(a)-turn motif, a conformation found for many cyclic heptapeptides. Detailed biological tests of the synthetic compounds in different human cancer cell lines indicates these axinastatins to be inactive or of low activity.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800503
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  • 172
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    Synthesis via a Carbohydrate-Derived Münchnone of Pyrrolopyridines (Indolizines) and imidazopyridines, and their evaluation as inhibitors of β-D-glucosidasesDedicated to Oscar Jeger on the occasion of his 80th birthday (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1443-1456 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the presence of activating agents, the N-acylglycine 8 reacts with electrophilic alkynes via the münchnone9 to the pyrrolopyridines (= indolizines) 10, 18, and 19 (Scheme 1 ), Depending on the nature of the activating agent and the reaction temperature, the formation of the pyrroles was accompanied by partial epimerization to the manna-configurated epimers 16 and 17. The gluco-configurated pyrrolopyridine 10 was deprotected to 12. Silylation of 12, followed by reduction and desilylation, gave the hexol 15. Cycloaddition of 9 to 4-toluenesulfonyl cyanide yielded 53% of the imidazole 23, while cycloaddition to phenyl cyanate gave the phenoxyimidazole 28 in low yields only (Scheme 2). As expected, the deprotected pyrroles 12, 15, 20, and 21 are weak inhibitors of retaining β-glucosidases, while the deprotected imidazole 24 derived from 23 proved a good inhibitor of sweet-almond β-glucosidases and a powerful inhibitor of Caldocellum saccharolyticum β-glucosidase.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800509
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  • 173
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    Introduction of Amino Alcohols in the Ring-Opening Reaction of 3-bromo-2,5-dimethylthiophene 1,1-dioxide. A short diastereoselective synthesis of substituted ‘tetrahydrobenzo[a]pyrrolizidines’ (= octahydro-1H-pyrrolo[2,1-a]isoindoles) using L-prolinolDedicated to Prof. Dr. h. c. Dieter Seebach on the occasion of his 60th birthday (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1483-1493 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrahydrobenzo[a]pyrrolizidines (= octahydro-1H-pyrrolo[2,1-a]isoindoles) and tetrahydrobenzo[a]indo-lizidines, (= decahydropyrido[2,1-a]isoindoles) were prepared stereoselectively in four steps through an amineinduced ring-opening of 3-bromo-2,5-dimethylthiophene 1,1-dioxide (1) with L-prolinol (9), piperidine-2-methanol (10), and piperidine-2-ethanol (11), yielding the dienes (2S)-1-[(2E,4Z)-4-bromohexa-2,4-dienyl]pyrrolidine-2-methanol (12), 1-[(2E,4Z)-4-bromohexa-2,4-dienyl]piperidine-2-methanol (13), and 1-[(2E,4Z)-4-bromo-hexa-2,4-dienyl]piperidine-2-ethanol (14; Scheme2), which, after conversion into their α,β-unsaturated esters, cyclized in a TiCl4-catalyzed intramolecular Diets-Alder reaction (Scheme3). A discussion on the mechanism of the ring opening reaction including semiempirical and ab initio calculations is also presented.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19970800512
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  • 174
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    X-Ray Structure Analyses of Alkyl-Substituted N-Acryloyl- and N-CrotonoyltoluenesultamsDerived from saccharine (= 1,2-benzoisothiazol-3(2H)-one, 1,1-dioxide)Dedicated to the memory of Professor Wolfgang Oppolzer (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1607-1612 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The X-ray crystal-structure analyses of two N-enoyl-toluenesultam derivatives 1 are reported. The structural differences with their bornanesultam analogues 2 as well as stereochemical aspects with respect to their [4 + 2] and [3 + 2] cycloadditions are discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800518
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  • 175
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    Boophiline, an Antimicrobial Sterol Amide from the cattle tick boophilus microplus (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2066-2072 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Boophiline (1), a new sterol amide was isolated from the cattle tick Boophilus microplus (Ixodidae). The structure was assigned as N-[3-(sulfooxy)-25ξcholest-5-en-26-oyl]-L-isoleucine by detailed 2D NMR investigations in conjunction with FAB mass spectrometry and acidic hydrolyses. Complete assignment of the diastereotopic methylene protons of the ring system could be deduced from the NMR data. In agar dilution assays, 1 exhibited antifungal properties against Cladosporium cucumerinum and antibacterial activity against Bacillus subtilis and Escherichia coli.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19970800707
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  • 176
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    Comparative Study of the Cope rearrangement of hexa-1,5-diene and barbaralane (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2112-2123 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The classical rules for Cope rearrangements predict a transition state with chair form to be favored over the boat form. On the other hand, bridged homotropylidenes, which allow only a boat-form transition state by steric reasons, have extremely low barriers. A controversy about the correct pathway and the different possible intermediates and transition states of the reaction has gone on for years. In this work, the hypersurfaces of barbaralane, in comparison with the boat- and chair-form of hexa-1,5-diene, are computed by the ab inito CASSCF (6,6)/6-31G** method starting with UMP2/6-31G** natural orbitals (NO's). All three hypersurfaces show characteristic features, and, moreover differ from each other. A hitherto undiscussed intermediate, bicyclo[2.2.0]hexane, was localized on the boat-hexa-1,5-diene pathway. So it is noteworthy that our transition state for the boat-hexa-1,5-diene does not correspond to the transition states found by other authors for this conformation. The computed enthalpies of activation of boat- and chair-hexa-1,5-diene, and barbaralane are in good agreement with the experimental data.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19970800711
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  • 177
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    Novel Leptomycins from a Streptomyces strain A92-308902: Inhibitors of the Nucleo-cytoplasmic translocation of the HIV-1 regulatory protein Rev (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2157-2167 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As one of the regulatory gene products in the HIV-1 genome, Rev protein must be translocated from the nucleus to the cytoplasm to exert its function. Therefore, inhibition of Rev protein translocation could be a useful target for HIV therapy. An extract from the Streptomyces strain A92-308902 with very potent inhibitory activity was found in the course of a high throughput screening with a Rev translocation assay (RTA). Bioassay-guided fractionation with gel filtration, normal-phase and reversed-phase chromatography yielded six RTA-active metabolites belonging to the leptomycin family, the known leptomycin A (1), leptomycin B (2), kazusamycin B (3), and kazusamycin A (4). and the hitherto unknown dilactonmycin (5) and delactonmycin (6), together with an inactive cyclic hexadepsipeptide L-156,620 (7). The structures were established mainly by spectroscopic methods (UV, FT-IR, FAB-MS, 1H-NMR, 13C-NMR(JMOD), DQ-COSY, ROESY, HSQC, and HMBC). The configuration of all C=C bonds of 1-6 was unambiguously established by analysis of coupling constants and ROESY spectra. All isolated leptomycins 1-6 inhibit Rev translocation at nanomolar concentrations. Six derivatives (2a-c and 4a-c) of leptomycin B (2) and kazusamycin A (4) were also prepared and tested in the RTA for preliminary investigations on structure-activity relationships.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19970800715
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  • 178
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    The Enantioselective Copolymerisation of allylbenzene, 1-allyl-4-(trifluoromethyl)benzene, and 1-allyl-4-methoxybenzene with carbon monoxide (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2204-2214 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The olefins mentioned in the title were copolymerized with CO in the presence of palladium catalysts modified with dicyclohexyl{(R)-1-[(S)-2-(diphenylphosphino)ferrocenyl]ethyl}phosphine. Productivities up to 95 g/(gPd · h) were achieved. The obtained copolymers were recovered in the pure, regio- und stereoregular polyketone structures3. The isotactic poly[2-benzyl-1-oxopropane-1,3-diyl] (3a) and its analogues 3b, c were found to isomerize to the corresponding spirocyclic poly[3-(arylmethyl)tetrahydrofuran-2,2-5,5-tetrayl-2-oxy-2-methylene]s 4 in a suspension in CHC13, thus indicating that the spiroketal structure is thermodynamically the most stable for these copolymers. However, the atactic material did not undergo any structural transformation. These results show that regularity at the centers of chirality in the main chain is a prerequisite for the conversion of the polyketone to the spiroketal structure.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800719
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  • 179
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    Methyl and Phenylmethyl 2-Acetyl-3-{[2-(dimethylamino)-1-(methoxycarbonyl)ethenyl]amino}prop-2-enoate in the Synthesis of heterocyclic systems: Preparation of 3-amino-4H-pyrido-[1,2-a]pyrimidin-4-ones (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2418-2425 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl 2-acetyl-3-{[2-(dimethylamino)-1-(methoxycarbonyl)ethenyl]amino}prop-2-enoate (4) and phenyl-methyl 2-acetyl-3-{[2-(dimethylamino)-1(methoxycarbonyl)ethenyl]amino}prop-2-enoate (5) were prepared in three steps from the corresponding acetoacetic esters, and used as reagents for the preparation of N3-protected 3-amino-4H-pyrido[1,2-a]pyrimidin-4-ones 10-12, 5H-thiazolo[3,2-a]pyrimidin-5-one 13, 4H-pyrido[1,2-a]-pyridin-4-one 19 and 2H-1-benzopyran-2-ones 20-23. Free 3-amino-4H-pyrido[1,2-a]pyrimidin-4-ones 24-26 were prepared from 10-12 by removal of the 2-(methoxycarbonyl)-3-oxobut-1-enyl or 3-oxo-2-[(phenyl-methoxy)carbonyl]but-1-envl as N-protecting group by various methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800811
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  • 180
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    New Cyclophanes as Initiator Cores for the Construction of Dendritic Receptors: Host-guest complexation in aqueous solutions and structures of solid-state inclusion compounds (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2368-2390 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclophanes 3 and 4 were prepared as initiator cores for the construction of dendrophanes (dendritic cydophanes) 1 and 2, respectively, which mimic recognition sites buried in globular proteins. The tetra-oxy[6.1.6.1]paracyclophane 3 was prepared by a short three-step route (Scheme 1) and possesses a cavity binding site shaped by two diphenylmethane units suitable for the inclusion of flat aromatic substrates such as benzene and naphthalene derivatives as was shown by 1H-NMR binding titrations in basic D2O phosphate buffer (Table 1). The larger cyclophane 4, shaped by two wider naphthyl(phenyl)methane spacers, was prepared in a longer, ten-step synthesis (Scheme 2) which included as a key intermediate the tetrabromocyclophane 5. 1H-NMR Binding studies in basic borate buffer in D2O/CD3OD demonstrated that 4 is an efficient steroid receptor. In a series of steroids (Table 1), complexation strength decreased with increasing substrate polarity and increasing number of polar substituents; in addition, electrostatic repulsion between carboxylate residues of host and guest also affected the binding affinity strongly. The conformationally flexible tetrabromocyclophane 5 displayed a pronounced tendency to form solid-state inclusion compounds of defined stoichiometry, which were analyzed by X-ray crystallography (Fig. 2). 1,2-Dichloroethane formed a cavity inclusion complex 5a with 1:1 stoichiometry, while in the 1:3 inclusion compound 5b with benzene, one guest is fully buried in the macrocyclic cavity and two others are positioned in channels between the Cyclophanes in the crystal lattice. In the 1:2 inclusion compound 5c, two toluene molecules penetrate with their aromatic rings the macrocyclic cavity from opposite sides in an antiparallel fashion. On the other hand, p-xylene (= 1,4-dimethylbenzene) in the 1:1 compound 5d is sandwiched between the cyclophane molecules with its two Me groups penetrating the cavities of the two macrocycles. In the 1:2 inclusion compound 5e with tetralin (= 1,2,3,4-tetrahydronaphthalene), both host and guest are statically disordered. The shape of the macrocycle in 5a-e depends strongly on the nature of the guest (Fig. 4). Characteristic for these compounds is the pronounced tendency of 5 to undergo regular stacking and to form channels for guest inclusion; these channels can infinitely extend across the macrocyclic cavities (Fig. 6) or in the crystal lattice between neighboring cyclophane stacks (Fig. 5). Also, the crystal lattice of 5c displays a remarkable zig-zag pattern of short Br…O contacts between neighboring macrocycles (Fig. 7).
    Additional Material: 7 Ill.
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  • 181
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    Use of the Wolff Rearrangement of Diazo Ketones from Amino Acids as a synthetic method for the formation of oligonucleo-peptides: A novel approach to chimeric biomolecules (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 1-13 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photolysis and Ag-benzoate-catalyzed decomposition of the diazo ketones 2 and 4 derived from Z-Ala-OH and Z-Ala-Ala-OH in the presence of oligonucleotide derivatives bearing at the 5′-terminus an NH2 instead of the OH group, or an aminohexyl phosphate group lead to Z-protected 3-aminobutanoyl and to Z-Ala-β-HAla derivatives, respectively (conjugates 12, 13, and 17-23, Schemes 3-5), In solution, this amide-forming acylation reaction could be realized only with oligomers containing up to 8 unprotected nucleotide building blocks (Schemes 3 and 4). With the analogous polymer-bound and protected oligonucleotide derivatives as amino nucleophiles, excellent yields were obtained with all chain lengths tested (up to 15mer Scheme 5), The products were purified by reversed-phase HPLC and characterized by MALDI-TOF mass spectrometry (Figs. 2-4, Table 2) and by capillary gel electrophoresis (Fig.2).
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19970800102
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  • 182
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    A Novel and Efficient Approach for the Combinatorial Synthesis of Structurally Diverse Pyrimidines on solid supportPresented in part at the ‘Random & Rational Conference’ in Princeton on September 16, 1996 (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 65-72 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe a versatile novel approach for the synthesis of 2, 4, 6-trisubstituted pyrimidines on solid support. Thus, polymer-boun J thiouronium salt 2 reacted in high yield in a cyclocondensation reaction with the acetylenic ketones 3 to form, after tert-butyl-ester cleavage, the polymer-bound carboxylic acids 4, which were cleaved by oxidation with 3-chloroperbenzoic acid and pyrrolidine to form the 2-pyrrolidinylpyrimidine-4-carboxylic acids 6a-c in high yields and purities without further purification (Scheme 1). Alternatively, acid 4a was subjected to an Ugi four-component condensation which gave the polymer-bound Ugi products 9a-e in good yields (Scheme 2). Multidirectional cleavage reaction of sulfone 8a with different nucleophiles resulted in the clean formation of pyrimidine-4-carboxamides 10-13 (Scheme 3). This strategy combines efficiently solid-phase chemistry with a multicomponent reaction and a multidirectional cleavage step to form highly diverse pyrimidines in a parallel array.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19970800106
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  • 183
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    6-Azabicyclo[3.1.0]hex-30-en-2-ol Derivative, photochemically generated building blocks for bicyclic β-lactamsDedicated to Fabian Gerson to commemorate a long-standing collaboration (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 121-127 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds 4 are obtained by photolysis of simple N-alkylpyridinium salts in H2O or alcohol. On reaction with [Fe2(CO)9] in THF, 4 gives bicyclic tricarbonyliron complexes 13a-d, which on oxidative decomplexation with ceric ammonium nitrate afford cis-fused cyclopenteno-β-lactams 15a-d.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19970800112
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  • 184
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    Models for the Active Center of Pterin-Containing Molybdenum Enzymes: Crystal structure of a molybdenum complex with sulfur and pterin ligands (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 103-110 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first crystal structure of a molybdenum complex 9 with a hydrogenated pterin and a sulfur ligand contributes to the discussion about the active center of molybdenum and tungsten enzymes containing a molybdopterin cofactor. Complex 9 was synthesized through a redox reaction of [MoVIO2 (LN-S2)] (8; LN-S2 = pyridine-2, 6-bis(methanethiolato)) with 5, 6, 7, 8-tetrahydropterin (7). 2 HCl (H4Ptr.2 HCl). The complex crystallizes, with a non-coordinating Cl-atom acting as a counterion, in the monoclinic space group C2/c (No. 15) with cell dimensions a = 22.900(5), b = 10.716(2), c = 17.551(4) Å, β = 120.36(3)°, and Z = 8. We interpret 9 as [MoIVO(LN-S2)(H+-q-H2Ptr)]Cl (q = quinonoid; H2Ptr = dihydropterin), i.e., a MoIV monooxo center coordinated by a pyridine-2, 6-bis(methanethiolato) ligand and a protonated dihydropterin. The spectroscopic properties of this new complex are comparable to those of other crystalline molybdenum complexes of hydrogenated pterins without additional S-coordination. The slightly H2O-soluble complex 9 reacts with the natural enzyme substrate DMSO very slowly, possibly due to the lack of easily dissociable ligands at the metal center.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19970800110
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  • 185
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    Cyclo-β-peptides: Structure and tubular stacking of cyclic tetramers of 3-aminobutanoic acid as determined from powder diffraction dataDedicated to Professor Hans Paulsen on the occasion of his 75th birthday (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 173-182 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solid-state structures of three stereoisomer, 1-3, of the cyclic tetramer of 3-aminobutanoic acid are presented. These cyclo-β-peptides were found to be highly insoluble materials, and it proved to be impossible to grow crystals of sufficient quality for X-ray single-crystal analysis. The samples of 1-3 were, however, suitable candidates for structure determination from powder diffraction data (Fig. 1), and the application of this method is described. All three isomers have been found to adopt tubular structures (Figs. 2-4) in a fashion similar to those already observed for certain cyclo-α-peptides. The stacks of 16-membered rings are held together by four nonlinear C=O…H—N H-bonds between pairs of molecules (Fig.5).
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19970800116
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  • 186
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    Partial Synthesis and Characterization of the Mono-and Diepoxides of β-Cryptoxanthin (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 221-229 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: β-Cryptoxanthin (1) was acetylated and then epoxidized with monoperoxyphthalic acid. After hydrolysis, repeated chromatography, and crystallization, (3S,5R,6S)-5,6-epoxy-β-cryptoxanthin (3), (3S,5S,6R)-5,6-epoxy-β-cryptoxanthin (4), (3R,5′R,6′R)-5′,6′-epoxy-β-cryptoxanthin (5), (3S,5R,6S,5′R,6′S)-5,6:5′,6′-diepoxy-β-cryp-toxanthin (6), and (3S,5S,6R,5′S,6′R)-5,6:5′,6′-diepoxy-β-cryptoxanthin (7) were isolated as main products and characterized by their UV/VIS, CD, 1H- and 13C-NMR, and mass spectra. The comparison of the carotenoid isolated from yellow, tomato-shaped paprika (Capsicum annuum var. lycopersiciforme flavum) with 3-5 strongly supports the structure of 3 for the natural product.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19970800120
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  • 187
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    Metal Complexes with Macrocyclic Ligands. Part XLIIIPart XLII [1]. Tetraazamacrocyclic nickel(II) and copper(II) complexes with aliphatic methylthio- and methoxy-substituted pendant chains (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 241-252 
    Details
    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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    URL: http://dx.doi.org/10.1002/hlca.19970800122
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  • 188
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    Masthead (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997) 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800201
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  • 189
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    Synthesis of Indole Derivatives by [2 + 2] Photocycloaddition of Indoline-2-thiones with alkenes and photodesulfurization of indoline-2-thiones (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 388-397 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photochemical synthesis of indole derivatives starting from the indoline-2-thiones 1 is described. Irradiation of indoline-2-thiones 1 in the presence of alkenes 3 gave 2-alkyl-3H-indoles 4-7 or 2-alkylindoles 8-22 through the ring cleavage of the intermediates, spirocyclic amino-thietanes, initially derived by [2 + 2] cycloaddition of the C=S bond of 1 and the C=C bond of 3. Irradiation of 1 in the presence of trialkylamines 26 gave desulfurization products 27-32 and unexpected 3-alkylindoles 33-40. N-Acylindoline-2-thiones 11-p yielded the deacylated products, indoline-2-thiones 1a-b, and ethyl esters 43 through γ-H abstraction by the excited thioamide S-atom when irradiated in CDC13/EtOH or benzene/EtOH. Oxygen analogues 2a-d also underwent intramolecular H abstraction to give the indolin-2-ones 2e-f and ethyl esters 43 in a similar way.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19970800205
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  • 190
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    Isolation, Structure, and Biological Activities of Long-Chain Catechols of Plectranthus sylvestris (Labiatae) (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 436-448 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Antioxidant activity guided fractionation of extracts of the aerial parts of the title plant and HPLC separation yielded a series of oxygenated long-chain alkylcatechols. Their structures were inferred by spectroscopic methods and chemical transformations to be the novel 4-[(2S,4R,6S)-4-(acetyloxy)tetrahydro-6-pentyl-2H-pyran-2-yl]benzene-1,2diol (1a), 4-[(2S,4R6S)-tetrahydro-4-hydroxy-6-pentyl-2H-pyran-2-yl]benzene-1,2-diol (1b), 4-[(3S,5S)-5-(acetyloxy)-3-hydroxydecyl]benzene-1,2-diol (2a), 4-[(3S,5S)3-(acetyloxy)-5-hydroxydecyl]benzene-1,2-diol (2b), (3S,13Z)-1-(3,4-dihydroxyphenyl)-3-hydroxydocos-13-en-5-one (3a), (Z)-1-(3,4-dihydroxyphenyl)docos-13-en-5-one (4), besides the known l-(3,4-dihydroxyphenyl)icosan-5-one (5). The absolute configurations of the optically active compounds which are structurally related to the [n]-gingerols (6) and -diols (7) were established by the high-field 1H-NMR application of Mosher's method. All compounds are in vitro potent antioxidants, inhibiting the Fe2+-catalysed autoxidation of linoleic acid in the same order of magnitude as the commercial antioxidant 2,6-di(tert-butyl)-4-methylphenol (BHT). The dose-dependent inhibitory effects on soybean-lipoxygenase are in the μmol range, that of the most effective compound (3a) in the nmol range, hence being significantly more potent than the Known anti-inflammatory and analgesic drugs indomethacin and nordihydroguaiaretic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800209
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  • 191
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    Synthesis and Structure of a Macrocyclic Europium Complex and its possible role as a catalyst for phosphodiester transesterification (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 487-494 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and X-ray crystal structure of a europium macrocyctic complex 1, an important catalyst used for the sequence-specific cleavage of RNA, is reported. The role of this metal complex in facilitating phosphate transesterification is discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800213
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  • 192
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    A Novel Approach towards 2,3,5-Trisubstituted Thiophenes via tandem Michael addition/intramolecular Knoevenagel condensation (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 531-537 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starting from the easily available, highly functionalized acetylenic ketories 4a-i (Scheme 1), novel 2,3,5-trisubstituted thiophenes 1a-i (Scheme 2) were synthesized in good yields using a tandem Michael-addition/intramolecular Knoevenagel-condensation strategy, featuring Cs2CO3/MgSO4 (1:2) as an efficient base to effect the cyclization. Subsequent simple one-step transformations yielded 2,3-disubstituted thiophene-5-carbaidehydes 7a-c, carboxylic-acid derivatives 8, 9, and 11, and alcohol 10 (Scheme 3). These molecules constitute interesting novel thiophene-containing building blocks, useful for the preparation of low-molecular-weight compound libraries by combinatorial and parallel-chemistry techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800217
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  • 193
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    Synthesis, Characterization, and Crystal Structure of Complexes of Lanthanide Picrates with N,N,N′,N′-tetraphenyl-3,6-dioxaoctanediamide (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 586-592 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lanthanide picrate complexes with the ligand N,N,N′,N′-tetraphenyl-3,6-dioxaactanediamide (tdd): [Ln(Pic)3(tdd)] (Ln = La, Nd, Eu, Tb, Er) have been prepared in a nonaqueous medium and characterized by elemental analysis, conductivity measurements, IR, and 1H-NMR spectra. The crystal structures of the complexes for Ln = Nd and Er were determined. The early lanthanide, NdIII, crystallizes as the nona-coordinate complex [Nd(Pic)3(tdd)]. 2 CH3CN in the monoclinic space group P21n with a = 11.384(2), b = 18.805(4), c = 27.526(5) Å, β = 99.41(1)°, V = 5832(2) Å3, and Dc = 1.58 gcm-3 for Z = 4. The structure was refined to R = 0.0505, based on 4772 observed Deflections. The late lanthanide, ErIII, forms an octa-coordinate complex [Er(Pic)3(tdd)]; crystals are triclinic, P1, with a = 12.449(2), b = 17.065(2), c = 26.243(4) Å, α = 72.12(1), β = 87.86(1), γ = 84.60(1)°, V = 5282(1) Å3, and Dc = 1.68 g cm-3 for Z, = 4. The structure was refined to R = 0.0469, based on 10666 observed reflections, The results reveal that tdd forms a ring-like structure with its four O-atoms, coordinating to the metal ions as multidentate ligand, together with one O-atom of the bidentate picrate. The structure of the complexes is greatly affected by the ionic radius due to participation of the picrates in coordination.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19970800221
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  • 194
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    Mitteilungen (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 622-622 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800225
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  • 195
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    Palladium-Catalysed Intramolecular Cyclisations of Olefinic Propargylic Carbonates and application to the diastereoselective synthesis of enantiomerically pure (-)-α-thujone (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 623-639 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intramolecular [Pd2(dba)3]/tri(2-furyl)phosphine-catalysed (dba = dibenzylideneacetone, PhCH=CHCOCH=CHPh) cyclisations of olefinic propargylic carbonates I provided alk-1-enyl-(3-aza)bicyclo[3.1.0]-hexanes VIII in good yields. A palladium cascade sequence I → II → III → IV → VII → VIII is proposed. Furthermore, chiral propargylic carbonates such as 23, 24 and 25 allowed diastereoselective formation of bicyclo[3.1.0]hexanes 29, 30 and 31, respectively. The first diastereoselective synthesis of the monoterpene, (-)-α-thujone 40 illustrates the potential of the method.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19970800302
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  • 196
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    Rogioldiol A, a new obtusane diterpene, and rogiolal, a degraded derivative, of the red seaweed Laurencia microcladia from II rogiolo along the coast of tuscany: A Synergism in Structural Elucidation (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 684-694 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of rogioldiol A ((-)-1), isolated from the red seaweed Laurencia microcladia, was determined. Employing the exciton-coupling technique for rogioldiol A p-bromobenzoate (2), the absolute configuration at C(9) of (-)-1 was assigned, and, together with extensive NMR experiments, the absolute configuration at C(10) and preferred conformations of (-)-1 were determined. The absolute configuration of the hetero-substituted cyclohexane ring was deduced in analogy from the X-ray structure of 4, a derivative of the aldehyde 3, which was isolated from the same seaweed and is believed to be a degradation product of (-)-1.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19970800306
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  • 197
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    Synthesis and Photochromic Behaviour of Naphthopyrans, Pyranoquinolines, Pyranoquinazolines and Pyranoquinoxalines (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 725-738 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New chromenes annulated with different six-membered azaheterocycles were prepared, i.e., the 3H-pyra-no[3,2-f]quinolines 9/10 and 14, the 8H-pyrano[2,3-h]isoquinoline 11, the 8H-pyrano[3,2-f]quinazolme 12, the 8-H-pyrano[3,2-f]quinoxaline 13, and the 2H-pyrano[2,3-f]isoquinoline 15. The synthesis was achieved using conveniently substituted α,β-unsaturated aldehydes and organotitanium intermediates arising from azaheterocyclic phenols. Their photochromic behaviour (photocolouration yield, UV/VIS spectrum of photomerocyanines, rate constant of thermal bleaching) were studied besides those of corresponding naphthopyrans. The heterocycle effect and the role of substituents in the pyran moiety were investigated quantitatively through the study of the photochromic properties and the solvent effects. Diaryl-substituted azino-fused chromenes, especially isoquinoline derivatives, exhibit increased colourabilities and bathochromically shifted spectra for photomerocyanines which open up new prospects for photochromic applications.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800310
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  • 198
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    Selective N3- and 5′-O-Alkylation of 2′,3′-O-isopropylideneuridine with methyl iodide (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 851-855 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2′,3′-O-isopropylideneuridine (1) reacts with MeI in the presence of an excess of NaH in THF giving 2′,3′-O-isopropylidene-5′-O-methyluridine (2). Prolonged reaction time gives rise to 2′,3′-O-isopropylidene-3,5′-O-dimethyluridine (4). The use of an equimolar amount of base and alkylating agent results predominantly in methylation at N(3) (→ 3).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800319
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  • 199
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    A Short Synthesis of the Factor-Xa Inhibitor DX-9065a using palladium-catalyzed key stepsPart of the Ph. D. Thesis of C. Kehr, University of Heidelberg, 1996Dedicated to Professor Dr. Rolf Gleiter, Heidelberg, on the occasion of his 60th birthday with best wishes (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 892-896 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe a new, efficient synthesis of DX-9065a (4), a potent inhibitor of the blood coagulation enzyme factor Xa (fXa) which has previously been prepared in more than 20 steps. We saved approximately 10 steps starting with a Pd-catalyzed cyanation of the triflate 10 of 7-methoxynaphthalen-2-ol (9). After cleavage of the MeO group with boron tribromide, the triflate 6 was coupled to acrylate 5 in a Heck reaction (→3). The subsequent transformations led to DX-9065 a.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800322
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  • 200
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    Metal Complexes with Macrocyclic Ligands. PartXLVPart XLIV: [1] Axial coordination tendency in reinforced tetraazamacrocyclic complexes (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 948-959 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800326
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