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  • 1995-1999  (2,904)
  • 1975-1979  (4,020)
  • 1935-1939  (1,958)
  • 1920-1924  (1,159)
  • Organic Chemistry  (9,230)
  • Electron microscopy
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  • 1
    Electronic Resource
    Electronic Resource
    Intimal-type primary sarcoma of the aorta (1999)
    Springer
    Virchows Archiv 435 (1999), S. 62-66 
    Details
    ISSN: 1432-2307
    Keywords: Key words Rhabdomyosarcoma ; Aorta ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We report an intimal sarcoma presenting as an aortic aneurysm. A 68-year-old man suffered from chest pain and speech disturbance. Computed tomography showed a sacciform aneurysm of the aorta, which was resected, revealing a polypoid tumour measuring 1.5×2×2.5 cm projecting into the lumen. This proved to be a poorly differentiated high-grade sarcoma having morphological, immunophenotypic and ultrastructural features consistent with rhabdomyosarcomatous differentiation. Primary sarcomas of the aorta are extremely rare. Many cases have been diagnosed as ”intimal” on the basis of their site of origin, and they are not easy to classify from their histological pattern. Electron microscopy and the use of a more comprehensive panel of immunohistochemical markers should be applied in the histological classification of ”intimal” sarcoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050396
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  • 2
    Electronic Resource
    Electronic Resource
    Melanin pigmented oncocytic metaplasia of the nasopharynx (1999)
    Springer
    Virchows Archiv 434 (1999), S. 455-457 
    Details
    ISSN: 1432-2307
    Keywords: Key words Melanin ; Oncocytic metaplasia ; Nasopharynx ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A 64-year-old man presented with a history of discomfort of the throat of a few weeks’ duration. Nasoscopic examination revealed multiple small, brown pigmentations at the left suprapharynx, the base of the left nasal cavity and the pharyngeal openings of the auditory tube on both sides. Microscopically, the lesion showed a glandular pattern of oncocytic epithelium with abundant pigmented granules and melanophages in the surrounding stroma. Immunohistochemically, the dendritic cells in the basal layer were positive for S-100 protein. Electron microscopic study revealed numerous fully melanized melanosomes and hypertrophied mitochondria in the oncocytic cells. Oncocytic cells do not produce melanin for themselves, melanin granules apparently being transferred from the adjacent dendritic cells to the oncocytic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050366
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  • 3
    Electronic Resource
    Electronic Resource
    A developmental study using three antibodies (VOBM1, VOBM2, and VOM2): immunocytochemical and electron microscopical analysis of the luminal surface of the rat vomeronasal sensory epithelium (1999)
    Springer
    Anatomy and embryology 199 (1999), S. 215-224 
    Details
    ISSN: 1432-0568
    Keywords: Key words Vomeronasal organ ; Microvilli ; Monoclonal antibody ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The development of the rat vomeronasal organ was studied morphologically and immunocytochemically, using the monoclonal antibodies (MAbs) VOBM1, VOBM2 and VOM2 that react with the luminal surface of the vomeronasal sensory epithelium. Postnatal day (P) 7, 14, 21, 28, 35 and adult animals were examined. The vomeronasal organ and the blood vessel of the organ markedly increased in size and the vomeronasal glands increased in number between P7 and P14. At P35, the shape of the vomeronasal organ was similar to that of the adult but its size was slightly smaller. Electron microscopy showed that only a few scattered microvilli were present on supporting cells, and receptor cells were immature at P7. At P21, well-branched microvilli of the receptor cells and many microvilli of the supporting cells were observed on the luminal surface of the sensory epithelium. At P35, most apical endings of supporting cells and receptor cells were covered with numerous microvilli. Less developed areas were also present at the luminal surface of the epithelium at P35. At P7, immunoreactivities of the three antibodies were observed as discontinuous thin-layered bands only on the luminal surface of the sensory epithelium and no immunoreactivity was observed in other regions of the vomeronasal organ. Immunoreactivities of the VOBM1, VOBM2 and VOM2 increased with age and were observed as continuous thin-layered bands on the luminal surface of the epithelium by P35. These finding suggest that the development of the vomeronasal organ continues after birth and that the organ may reach maturity just before puberty (P42–49).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050222
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  • 4
    Electronic Resource
    Electronic Resource
    A new combined Bodian-Luxol technique for staining unmyelinated axons in semithin, resin-embedded peripheral nerves: a comparison with electron microscopy (1999)
    Springer
    Acta neuropathologica 98 (1999), S. 323-329 
    Details
    ISSN: 1432-0533
    Keywords: Key words Unmyelinated fibers ; Peripheral nerve ; Electron microscopy ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Quantitation of unmyelinated fibers (UF) in peripheral nerves has classically relied upon ultrastructural morphometry. Because this method is time-consuming, it is not typically performed in routine analysis of nerve biopsies. We applied the Bodian-Luxol technique to detect unmyelinated axons by light microscopy on semithin sections from resin-embedded nerve tissue. Estimates were compared to ultrastructural counts. The staining appeared highly specific for axons. Excellent correlation was found between optic densities and the population of UF larger than 0.5 μm. The smallest profiles detected by light microscopy had a diameter close to 0.6 μm. This new technique is not a substitute for ultrastructural quantitative morphometry of UF, as very small unmyelinated axons, especially regenerating ones, can not be reliably visualized. However, it provides a valuable light microscopic method for evaluating axonal loss among UF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010051088
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  • 5
    Electronic Resource
    Electronic Resource
    Breached cerebral glia limitans-basal lamina complex in Fukuyama-type congenital muscular dystrophy (1999)
    Springer
    Acta neuropathologica 98 (1999), S. 330-336 
    Details
    ISSN: 1432-0533
    Keywords: Key words Micropolygyria ; Electron microscopy ; Frontal lobe ; Perivascular space ; Dot-like structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have reported breaches of glia limitans (GL)-basal lamina (BL) complex with protruding neuroglial tissue in Fukuyama-type congenital muscular dystrophy (FCMD) fetus brain and suggested that some basic deficits in the GL-BL complex may have a pivotal role in formation of micropolygyria in FCMD. We therefore investigated the cerebral GL-BL complex in seven FCMD cases (12–27 years of age), in three cases of Duchenne muscular dystrophy (17–25 years of age) and in two non-neurological controls (28 and 33 years of age). The frontal lobe cortex was examined immunocytochemically using antibodies against collagen type IV and laminin in each case, and ultrastructurally in an adult case of FCMD. In FCMD, the BL of the cortical surface was frequently breached with protruding neural tissue that ultrastructurally showed frequent synapses, neurites that had parallel arranged microtubules, and astrocytic processes. The outermost surface of this tissue was only partly lined by a BL. In the region of the gyral adhesion of micropolygyria, the perivascular space of the apparently entrapped meningeal blood vessels was occupied by neuroglial tissue, which is assumed to have invaded through the occasionally seen breaches of the perivascular GL-BL complex. Electron microscopy of the intruding tissue showed frequent synapses, microtubule-containing neurites and astrocytic processes. No breached GL-BL complex was found in any of the non-FCMD cases. These findings indicate that in FCMD, the cerebral GL-BL complex continues to have a crucial deficit with resulting breaches through which neuroglial tissue protrudes, promoting adhesion of the adjacent cerebral gyri during brain development before and after birth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010051089
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  • 6
    Electronic Resource
    Electronic Resource
    Motor neuron disease with predominantly upper extremity involvement: a clinicopathological study (1999)
    Springer
    Acta neuropathologica 98 (1999), S. 645-650 
    Details
    ISSN: 1432-0533
    Keywords: Key words Amyotrophic lateral sclerosis ; Autopsy ; Electron microscopy ; Immunocytochemistry ; Motor ; neuron disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report two autopsy cases of motor neuron disease (MND) patients with an unusual type of muscular atrophy predominantly affecting the shoulder girdle and the upper extremities with proximal dominance. Both patients are considered to be clinically categorized into the El Escorial suspected form of amyotrophic lateral sclerosis (ALS). At autopsy, they showed marked loss of spinal anterior horn cells accompanied by astrogliosis positively immunostained with anti-glial fibrillary acidic protein antibody at the cervical level. At the lumbosacral level, anterior horn neurons were relatively well preserved and Bunina bodies, ubiquitin-positive skein-like inclusions and Lewy body-like inclusions were observed in the remaining neurons. In one patient, brain stem motor neurons (nerves V, VII, XII) and motor cortex, including Betz cells, were also affected and the corticospinal tracts were degenerated at the level of the thoracic and lumbar spinal cord. Pathological findings of this patient are consistent with those of ALS. In the other patient, the motor cortex, brain stem motor nuclei and the corticospinal tracts were well preserved, which is pathologically compatible with progressive spinal muscular atrophy. These patients with such a peculiar pattern of progressive muscular atrophy should be placed in a subgroup of ALS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010051131
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  • 7
    Electronic Resource
    Electronic Resource
    Subretinal macrophages in the developing eye of eutherian mammals and marsupials (1999)
    Springer
    Anatomy and embryology 200 (1999), S. 551-558 
    Details
    ISSN: 1432-0568
    Keywords: Key words Retina ; Development ; Retinal pigment epithelium ; Microglia ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Blood-borne mononuclear cells invade the developing retina via the hyaloid vasculature at the optic nerve head. Following removal of apoptotic cell debris they give rise to the network of resident microglia. The population of cells recently described in the peripheral subretinal space of developing human eyes may represent a further population of macrophages destined to become microglia. The aim of the present study was to confirm the presence of subretinal macrophages in the developing eye in other mammalian species and perform preliminary immunophenotypic analysis in rat tissues. The range of species chosen included eutherian mammals (rat and rabbit) and marsupials (wallaby and opossum). Ocular tissues from a range of developmental stages were studied by scanning electron microscopy and transmission electron microscopy. Distinctive networks of dendriform and pleomorphic macrophages were observed by scanning electron microscopy in the peripheral subretinal space of D2 rabbits, newborn and D2 rats and D75 wallaby. Transmission electron microscopic studies of D2 rabbit, newborn and D2 rat and all ages of North American opossum revealed cells with the ultrastructural features of macrophages in the peripheral subretinal space, cilio-retinal junction and between ciliary epithelial cells. Preliminary immunoperoxidase studies using a panel of anti-leukocyte monoclonal antibodies on frozen sections of rat ocular tissues (newborn, D2 and D4) revealed ED1+ Ox42+ ED2+ but Ox6– cells in the peripheral subretinal space, peripheral retina and ciliary body epithelia. The data confirms that subretinal macrophages are a feature of the developing eye in a broad range of mammalian species and immunophenotypic evidence leads the author to postulate that these cells arise from the ciliary body vasculature and may migrate into peripheral neural retina and mature into resident microglia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050303
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  • 8
    Electronic Resource
    Electronic Resource
    Magnetic properties of human liver and brain ferritin (1999)
    Springer
    European biophysics journal 28 (1999), S. 263-267 
    Details
    ISSN: 1432-1017
    Keywords: Key words Human liver ; Human brain ; Ferritin ; Electron microscopy ; Mössbauer spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Human brain (globus pallidus) and liver tissues were investigated by means of electron microscopy (EM), Mössbauer spectroscopy (MS) and SQUID magnetometry techniques. Based on MS measurements, the iron present was identified to be in the ferritin-like form (61–88%) and in the form of a low-spin iron species (the balance). Its overall concentration was estimated as 1.5(3) mg in the brain and 2.4(5) mg in the liver, per gram of lyophilized tissue. The average core diameter was determined by EM measurements to be equal to 7.5(1.3) nm for the liver and 3.3(5) nm for the brain. Magnetization measurements carried out between 5 and 300 K yielded an estimation of an average blocking temperature, KT BL, as equal to 6.7 K and 8.5 K for the liver and the brain, respectively. From the dependence of KT BL on the external magnetic field it was concluded that the ferritin-like cores in the studied samples can be regarded as non-interacting particles. Finally, the uniaxial magnetic anisotropy constant was determined to be 6×103 J/m3 for the liver and 4×104 J/m3 for the brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002490050208
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  • 9
    Electronic Resource
    Electronic Resource
    Infraterminal spreading and extrajunctional expression of nicotinic acetylcholine receptors in denervated rat skeletal muscle (1999)
    Springer
    Experimental brain research 125 (1999), S. 426-434 
    Details
    ISSN: 1432-1106
    Keywords: Key words Acetylcholine receptor ; Nicotinic ; Denervation supersensitivity ; Neuromuscular junction ; α-Bungarotoxin ; Immunocytochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Through the use of biotinylated-bungarotoxin and monoclonal antibodies, the nicotinic acetylcholine receptor (nAChR) was localized in the subneural apparatus of mammalian motor end plates of the flexor digitorum brevis muscle of the adult rat at the light and electron microscopic levels. Under normal conditions, nAChR was located in the primary post-synaptic membrane of the neuromuscular junction, and the depths of the junctional folds constituting the secondary post-synaptic membrane did not contain any nAChR. Up to 75 days after repeated transection of the related motor nerve (sciatic), there was no major alteration in the light-microscopic localization of junctional nAChR in the subneural apparatus, except for a moderate shrinkage and increased immunocytochemical reactivity of the subneural apparatus. At the electron microscopic level, however, immunocytochemical reactivity gradually occupied the entire extent of the secondary post-synaptic membrane, including the depths of the junctional folds, which exhibited extensive branching. In non-innervated portions of the muscle fibers, nAChR receptor appeared in a linear localization on the surfaces of denervated muscle fibers. This linear reaction was not continuous with the nAChR reaction of the motor end plates. It is concluded that denervation supersensitivity might not be due to spreading of junctional nAChR from the end-plate area, but rather to expression of nAChR in non-innervated portions of the muscle fiber and to the infraterminal (subsynaptic) spreading of nAChR into the depths of junctional folds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050699
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  • 10
    Electronic Resource
    Electronic Resource
    Recovery of synapses in axotomized adult cat spinal motoneurons after reinnervation into muscle (1999)
    Springer
    Experimental brain research 125 (1999), S. 19-27 
    Details
    ISSN: 1432-1106
    Keywords: Key words Nerve injury ; Nerve repair ; Retrograde reaction ; Regeneration ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Peripheral axotomy of adult cat spinal motoneurons induces a marked loss of synaptic boutons from the cell bodies and dendritic trees. The aim of the present study was to analyze the recovery of synaptic contacts in axotomized motoneurons following reinnervation into muscle. Adult cat spinal motoneurons were first deprived of their muscular contacts for 12 weeks and, then, allowed to reinnervate their target muscle. Two years later, regenerated motoneurons were labeled with horseradish peroxidase to allow quantitative ultrastructural analyses of the synaptic covering of the cell bodies and dendrites. Presynaptic boutons were classified according to their size and the shape of their synaptic vesicles. Results show that a recovery of synaptic covering occurs in the axotomized neurons after muscle reinnervation, but it affects various bouton types to different degrees. The number of S-type boutons synapsing with the soma was 70% higher after reinnervation than at 12 weeks after axotomy, while the number of F-type boutons had increased by only 13%. Compared with the normal situation, the number of S-type boutons synapsing with the proximal dendrites increased from 82% at 12 weeks after axotomy to 180% in the reinnervated state. In conclusion, in adult cat spinal motoneurons, the reestablishment of muscular contact is followed by a normalization of some of the synaptological changes induced by a prolonged state of axotomy. In certain respects restitution is incomplete, but in others it results in overcompensation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050653
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  • 11
    Electronic Resource
    Electronic Resource
    Phase and aggregation behaviour of double-chain cationic surfactants from the class of N-alkyl-N-alkyl′-N, N-dimethylammonium bromide surfactants (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 856-867 
    Details
    ISSN: 1435-1536
    Keywords: Key words Double chain surfactants ; Aggregates ; Phase diagrams ; Lamellar phases ; Electron microscopy ; SANS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We present the phase diagrams and the properties of newly synthesised double-chain cationic N-alkyl-N-alkyl′-N,N-dimethylammonium bromide surfactants [C x C y DMABr (x = 12, 14 and 16; y = 10, 11, 12, 14 and 16)]. All the systems studied form liquid-crystalline lamellar phases but with different morphologies: unilamellar vesicles at low surfactant concentrations, multilamellar vesicles and tubular aggregates for surfactant concentrations between 2 and 10 wt% and at even higher concentrations planar bilayers of surfactant molecules in the classical Lα phase. The phase diagrams were determined with macroscopic and microscopic methods (polarisation microscopy, freeze-fracture transmission electron microscopy, scanning electron microscopy and differential interference contrast microscopy). The properties of the surfactant solutions were determined with differential scanning calorimetry measurements for Krafft point determination and small-angle neutron scattering measurements for interlamellar spacing and bilayer thickness. Finally, conductivity and viscosity measurements for phase characterisation were carried out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050462
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  • 12
    Electronic Resource
    Electronic Resource
    Synthesis of colloids and films of Pr, Er and Yb with nonaqueous solvents (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 164-173 
    Details
    ISSN: 1435-1536
    Keywords: Keywords Nanostructures ; Thin films ; Vapor deposition ; Electron microscopy ; Optical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Colloidal dispersions of Yb, Er and Pr have been prepared by chemical liquid deposition. The metals were cocondensed at 77 K with 2-methoxyethanol and ethanol to produce solvated metal atoms. The particle size of the dispersions was determined by transmission electron microscopy to range from 52 to 1080 Å; the particles had spherical shapes. After solvent evaporation under vacuum, active solids and amorphous powder were deposited over Cu and Al metal. Dispersion stability, particle size, UV/Vis absorption and zeta potential were studied. The solids prepared by solvent evaporation were characterized by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The films prepared on Al were studied by scanning electron microscopy. The most stable colloid was obtained using 2-methoxyethanol: several concentrations were stable for several months and the zeta potential indicated that this colloid stability is mainly due to solvation effects. FTIR spectroscopy of the solids indicated solvent incorporation in the film. This observation was corroborated by thermal analysis. Information on the thermal stability of the films was obtained by TGA. The UV/Vis absorption spectrum was measured at several concentrations under different conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050381
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  • 13
    Electronic Resource
    Electronic Resource
    Muscle and skin biopsies are a sensitive diagnostic tool in the diagnosis of CADASIL (1999)
    Springer
    Journal of neurology 246 (1999), S. 526-532 
    Details
    ISSN: 1432-1459
    Keywords: Key words CADASIL ; Cerebrovascular disease ; Skin biopsy ; Muscle biopsy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a microangiopathic syndrome. Although the defective gene has been identified, genetic analysis may be effort some due to its large size and various mutations. Providing a reliable diagnostic marker would therefore be helpful. Electron microscopy has revealed characteristic electron-dense granular deposits in the basal lamina of vessels of patients with CADASIL. We investigated the sensitivity of skin and muscle biopsies for diagnosing CADASIL. We examined 30 family members of three unrelated German families affected by CADASIL. In 14 of the 21 affected individuals we performed skin and muscle biopsies; two patients were clinically asymptomatic. Under electron microscopy all muscle and skin biopsy specimens showed patches of granular and electron-dense material in the basal layer of both arterioles and capillaries. These findings confirm that general microangiopathy is a typical feature of this syndrome and is present in the early phase of the disease with or without clinical manifestation. Thus, as electron microscopy of skin biopsy specimens can establish the diagnosis of CADASIL with high certainty, it may be considered the method of first choice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050398
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  • 14
    Electronic Resource
    Electronic Resource
    A comprehensive analysis of selected diagnostic methods with respect to their usefulness in evaluating the biology of neoplastic cells in patients with laryngeal cancer (1999)
    Springer
    European archives of oto-rhino-laryngology and head & neck 256 (1999), S. 306-311 
    Details
    ISSN: 1434-4726
    Keywords: Key words Laryngeal cancer ; p53 ; Oncoprotein ; Ki67 ; Proliferating cell nuclear antigen (PCNA) ; DNA ploidy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The difficult and complicated mechanism of cancer development with little knowledge about the biology of existing cancers can lead to a permanent search for new examination techniques to improve the precision of life expectancy in patients and the selection of the most efficient methods of treatment. The aim of this study was to analyze certain prognostic factors, i.e., p53, Ki67, proliferating cell nuclear antigen (PCNA), DNA ploidy and cell proliferating activity, as well as the degree of morphological differentiation and cell maturity evaluated on an ultrastructural level in patients with laryngeal cancers in connection with data obtained from follow-up examinations and the clinical course of the disease. Neoplastic tissue was taken from 120 patients with laryngeal cancers. All underwent surgical treatment, radiotherapy and combined treatment in the Department of Otolaryngology, Karol Marcinkowski University School of Medical Sciences, Poznań, Poland, and the Department of Otolaryngology – Head and Neck Surgery, Haukeland University, Bergen, Norway. Before beginning treatment all patients underwent histological verification of their neoplastic tissues. Histopathological examination proved that the majority of cases (95%) had a squamous cell carcinoma. The occurrence of changes within the lymph nodes of the neck (N) was significantly correlated with T, S, Ki67, metastases to lymph nodes, DNA ploidy, site and surgery performed. The degree of clinical progression (S) was intercorrelated with T, N, p53, Ki67, PCNA, DNA ploidy, site and laryngectomy. The occurrence of oncoprotein p53 in neoplastic cells was measured by the staining degree of their nuclei and was correlated with T, S, DNA ploidy, metastases to lymph nodes, PCNA and site. The degree of staining of neoplastic cells for the nuclear antigen Ki67 was correlated to T, N, G, S, DNA ploidy, metastases to lymph nodes and surgical treatment. The proliferative antigen PCNA in the examined population of patients was intercorrelated with T, p53, Ki67, metastases to lymph nodes and surgical treatment. The results obtained from DNA flow cytometry could be associated with N, G, p53, Ki67 and metastases to lymph nodes. On the basis of the results obtained, the techniques suggested for the morphological and biological evaluation of neoplastic cells in cancer of the larynx should include TNM classification + G + DNA + p53 + Ki67.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004050050252
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  • 15
    Electronic Resource
    Electronic Resource
    The cytoskeleton of the myenteric neurons during murine embryonic life (1999)
    Springer
    Anatomy and embryology 199 (1999), S. 459-469 
    Details
    ISSN: 1432-0568
    Keywords: Key words Differentiation ; Electron microscopy ; Histochemistry ; Microtubules ; Neurofilaments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The organization of the cytoskeleton has been studied during mouse differentiation in cells of the myenteric neuronal lineage. The entire gut was examined starting from day 12.5 of embryonic life (E12.5) until birth (P0). Immunocytochemistry was performed to evaluate the expression of five of the most represented neurofilaments proteins (the low, NF-L, medium, NF-M, and heavy, NF-H, molecular weight subunits, α-internexin and peripherin) and of two of the microtubule-associated proteins (MAP1 and MAP2a+2b). In parallel, the appearance in the differentiating myenteric neurons of filamentous and microtubular structures and their intracytoplasmatic distribution were observed under the electron microscope. A differential immunohistochemical expression of the structural proteins was found. Immature cells expressed α-internexin, peripherin, NF-M and MAP1 by day E12.5; α-internexin expression was strong in these cells, but gradually decreased with age and was practically absent in adulthood. Conversely, the expression of the other three proteins increased with cell differentiation and was still present in adulthood. NF-L and NF-H expression appeared later, by day E16.5, and was weak for the entire pre- and postnatal life. MAP2a+2b was never expressed. Under the electron microscope, at day E12.5 the cytoskeleton was already organized in filamentous and microtubular structures. At this age neurofilaments were few and mainly located in the cell processes, and microtubules were numerous and mainly assembled in the neuritic growth cones, together with synaptic vesicles. With ageing, neurofilaments and microtubules were ubiquitous in the neuron. Data obtained demonstrate that cytoskeletal proteins gradually accumulate in the cells of the neuronal lineage in parallel with the organization of the cytoskeletal structures, which in turn mediate important neural events by the earliest stages of murine embryonic life, including growth of nerve processes and initiation of axonal transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050244
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  • 16
    Electronic Resource
    Electronic Resource
    Outbreaks of gastroenteritis caused by SRSVs from 1987 to 1992 in Kyushu, Japan: Four outbreaks associated with oyster consumption (1999)
    Springer
    European journal of epidemiology 15 (1999), S. 175-180 
    Details
    ISSN: 1573-7284
    Keywords: Electron microscopy ; Epidemiology ; Non-bacterial Gastroenteritis ; Oyster ; Small round structured viruses (SRSVs)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract From 1987 to 1992, 18 outbreaks of acute non-bacterial gastroenteritis occurred in Kyushu district. The most common symptoms were diarrhea, vomiting, nausea and abdominal cramp. Small round structured viruses (SRSVs) were detected in 52 (44.8%) of 116 stool samples from 17 outbreaks by the electron microscopy (EM) method, and a significant increase in the antibody level was noted in 42 (80.7%) of 52 paired serum samples from 12 outbreaks by the immune electron microscopy (IEM) method and in 18 (51.4%) of 35 samples from 8 outbreaks by the western blot (WB) method. However, according to the WB method, antigen-antibody reaction was not observed to reference antigen strips (SRSV-9/Tokyo 86-510, 63kDa) in three of the 8 outbreaks. The detected virus was regarded as an etiologic agent for these outbreaks. In four of 5 outbreaks which appeared associated with eating raw oysters, there was a close relation between SRSV infection and consumption of raw oysters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007543924543
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  • 17
    Electronic Resource
    Electronic Resource
    Metaphase-specific cell death in meiotic spermatocytes in mice (1999)
    Springer
    Cell & tissue research 296 (1999), S. 359-369 
    Details
    ISSN: 1432-0878
    Keywords: Key words Apoptosis ; Electron microscopy ; Meiosis ; Spermatocytes ; Spermatogenesis ; Testis ; TUNEL ; Mouse (10 strains)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Apoptosis of male germ cells is a widespread but little-understood phenomenon in many animal species. The elucidation of its mechanisms could be useful in the understanding of male infertility. We have examined the distribution of dying cells with the terminal transferase-mediated nick-end labeling (TUNEL) method and by an electron-microscopic procedure in the testes of 10 mouse strains, viz., C57BL/10 (B10), SL/NiA (SL), C57BL/6 (B6), C3H/He (C3H), BALB/c (BALB), DBA2 (DBA), CBA/J (CBA), MRL/MpJ-+/+ (M+), MRL/MpJ-lpr/lpr (lpr), and wild-type NJL mice (Mus musculus musculus). In the testes of the B10, NJL, SL, B6, C3H, BALB, DBA, and CBA mice, very few TUNEL-positive cells are distributed in the seminiferous tubules, whereas in the testes of the M+ and lpr mice, many TUNEL-positive cells, which are restricted to stage XII seminiferous tubules, have been identified. The most important finding is that many metaphases of meiotic spermatocytes show a marked TUNEL-positive reaction. Some metaphases show apoptotic morphology electron-microscopically. These results suggest that the testes of MRL strains will provide a useful model for the study of the mechanism of metaphase-specific apoptosis in meiotic spermatocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051296
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  • 18
    Electronic Resource
    Electronic Resource
    Effect of high-level oxygen exposure on the peroxidase activity and the neuromelanin-like pigment content of the nerve net in the earthworm, Lumbricus terrestris (1999)
    Springer
    Cell & tissue research 295 (1999), S. 349-354 
    Details
    ISSN: 1432-0878
    Keywords: Key words Neuromelanin ; Neuron ; Peroxidase ; Oxygen metabolism ; High-definition light microscopy ; Electron microscopy ; Ultrastructure ; Cytochemistry ; Substantia nigra ; Lumbricusterrestris (Annelida)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Histochemical examination of 1-μm tissue sections from the dorsal nerve plexus of the earthworm, Lumbricus terrestris, reveals multiple brown intraneuronal granules. These granules contain material morphologically and histochemically consistent with neuromelanin. When viewed with transmission electron microscopy, these were seen as single membrane-enclosed biphasic granules with diameters of 370–730 nm. Exposure of L. terrestris to high-level environmental oxygen resulted in an increase in the number of neuromelanin-like pigment granules within the neurons of the circular muscle layer. As measured by ortho-phenylenediamine hydrochloride, the endogenous peroxidase activity of extracts from worms incubated in high-level environmental oxygen was 51% more than controls. The endogenous peroxidase activity was localized in situ with 3,3-diaminobenzidine (DAB) and was found to increase in and around the neuromelanin-like pigment-containing neurons within the circular muscle layer. These studies suggest that the nerve net of L. terrestris may serve as a model to study the role of neuromelanin production in oxidative stress and its relationship to endogenous peroxidases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051241
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  • 19
    Electronic Resource
    Electronic Resource
    Op/op mice defective in production of functional colony-stimulating factor-1 lack macrophages in muscularis externa of the small intestine (1999)
    Springer
    Cell & tissue research 295 (1999), S. 485-493 
    Details
    ISSN: 1432-0878
    Keywords: Key words Immunohistochemistry ; Electron microscopy ; Interstitial cells of Cajal ; F4/80 ; CSF-1 ; Kit-receptor ; Mouse (op/op)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The osteopetrotic (op/op) mutant mouse possesses an inactivating mutation in the colony-stimulating factor-1 (CSF-1) gene, which results in the absence of certain macrophages and in osteopetrosis, following a lack of osteoclasts. Studies of the op/op mouse indicate that CSF-1-dependent tissue macrophages may belong to a trophic and/or scavenger subpopulation, which through their effect on other cell types can significantly affect tissue functions, and that cells which are CSF-1 independent have antigen presentation and immunological functions.We have previously identified a cell system of regularly distributed macrophages in the muscularis externa of the small intestine and wanted to extend these studies to the op/op mouse.The present investigations with light- and electron-microscopic methods using fluorescent dextran, methylene blue and immunohistochemistry (F4/80, anti-kit receptor, anti-CD3, anti-CD45R/B220) show that macrophages are absent from the muscle layers, with only an occasional macrophage present in the subserosa. In the lamina propria and submucosa, macrophage numbers are reduced. In all other respects the muscularis externa appears normal, including normal organization and number of interstitial cells of Cajal. Control and op/op mice both lack cells expressing CD3 (T lymphocytes), CD45R/B220 (B lymphocytes) and mast cells in the muscularis externa. This leaves the muscularis externa macrophages as the most likely source of local cytokine production under such conditions as postoperative ileus and intussusception in infants, where the muscularis externa appears to be one target of cytokines. We conclude that the lack of macrophages, combined with the preservation of otherwise normal structure, will make the op/op mouse a valuable model by which to assess the functions and relative importance of the muscularis externa macrophages in relation to intestinal motility under normal and pathological conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051254
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  • 20
    Electronic Resource
    Electronic Resource
    Caveolin and its cellular and subcellular immunolocalisation in lung alveolar epithelium: implications for alveolar epithelial type I cell function (1999)
    Springer
    Cell & tissue research 295 (1999), S. 111-120 
    Details
    ISSN: 1432-0878
    Keywords: Key words Caveolin ; Caveolae ; Lung ; Alveolar epithelial type I cell ; Immunocytochemistry ; Electron microscopy ; Confocal laser scanning microscopy ; Rat (CD)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Caveolae are flask-shaped invaginations of the plasmalemma which pinch off to form discrete vesicles within the cell cytoplasm. Biochemically, caveolae may be distinguished by the presence of a protein, caveolin, that is the principal component of filaments constituting their striated cytoplasmic coat. Squamous alveolar epithelial type I (ATI) cells, comprising approximately 95% of the surface area of lung alveolar epithelium, possess numerous plasmalemmal invaginations and cytoplasmic vesicles ultrastructurally indicative of caveolae. However, an ultrastructural appearance does not universally imply the biochemical presence of caveolin. This immunocytochemical study has utilised a novel application of confocal laser scanning and electron microscopy unequivocally to localise caveolin-1 to ATI cells. Further, cytoplasmic vesicles and flask-shaped membrane invaginations in the ATI cell were morphologically identified whose membranes were decorated with anti-caveolin-1 immunogold label. Coexistent with this, however, in both ATI and capillary endothelial cells could be seen membrane invaginations morphologically characteristic of caveolae, but which lacked associated caveolin immunogold label. This could reflect a true biochemical heterogeneity in populations of morphologically similar plasmalemmal invaginations or an antigen threshold requirement for labelling. The cuboidal alveolar epithelial type II cell (ATII) also displayed specific label for caveolin-1 but with no ultrastructural evidence for the formation of caveolae. The biochemical association of caveolin with ATI cell vesicles has broad implications for the assignment and further study of ATI cell function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051217
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  • 21
    Electronic Resource
    Electronic Resource
    Types, numbers and distribution of synapses on the dendritic tree of an identified visual interneuron in the brain of the locust (1999)
    Springer
    Cell & tissue research 296 (1999), S. 645-665 
    Details
    ISSN: 1432-0878
    Keywords: Key words Descending contralateral movement detector (DCMD) ; Identified neuron ; Vesicles ; Electron microscopy ; 3-D reconstruction ; Locust ; Schistocercagregaria (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The descending contralateral movement detector (DCMD), an identified descending interneuron in the brain of the locust Schistocerca gregaria has been investigated by using light and electron microscopy. We describe the fine structure, distribution and numbers of synapes that it receives from another identified brain neuron, the lobular giant movement detector (LGMD), and from unidentified neurons. The DCMD dendrites emerging from the integrative segment vary in form and number between individuals and sexes but always form a flattened dendritic domain. The arborizations and the integrative segment appear to be exclusively postsynaptic. Two types of synaptic contacts (Type 1 and 2) onto the DCMD can be discerned as having either round (Type 1) or pleiomorphic synaptic vesicles (Type 2) and by large (Type 1) or small (Type 2) subsynaptic appositions. Contact zones of Type 1 synapses are smaller than those of Type 2. LGMD-synapses are of Type 1 and occur intermingled with presynaptic sites of unidentified units. Some branches of the DCMD receiving input from unidentified units are devoid of contacting LGMD processes. Synapses of both types are randomly distributed over the DCMD integrative segment and at fibres with similar sizes.Type 1 synapses are much more frequent than Type 2 synapses and their number is negatively correlated with fibre diameter. For a whole DCMD dendritic arborization, a total of 8500 active zones of chemical synapses has been calculated, including a mininum of 2250 LGMD-synapses and about 1000 Type 2 synapses. The DCMD may thus receive a considerable amount of input from as yet unidentified neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051325
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  • 22
    Electronic Resource
    Electronic Resource
    Docetaxel-induced apoptosis in the mitotic phase: electron microscopic and cytochemical studies of human leukemia cells (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 167-174 
    Details
    ISSN: 1437-773X
    Keywords: Key words Apoptosis ; Docetaxel ; Human leukemia cell ; DNA fragmentation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We induced apoptosis in cells of the human leukemia cell line HL-60 using an antitumor agent, docetaxel (Taxotere), and investigated apoptosis in various aspects using in situ end-labeling (ISEL) of DNA, DNA fragmentation assay, flow cytometry, and electron microscopy. Because it inhibits depolymerization of tubulin, docetaxel is thought to arrest the cell cycle at the mitotic stage and to exert an antitumor effect. In this study, accumulation of docetaxel-treated cells at the G2/M phase was detected using flow cytometry. On ISEL of DNA, DNA fragmentation was observed at the mitotic stage. On electron microscopy, the nuclei of apoptotic cells lost their nuclear membranes, as do cells at mitosis, demonstrating that the cells were arrested mainly at the M phase in the cell cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050024
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  • 23
    Electronic Resource
    Electronic Resource
    Electron microscopic and immunohistochemical studies of gastrointestinal stromal tumors (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 213-220 
    Details
    ISSN: 1437-773X
    Keywords: Key words Gastrointestinal stromal tumor ; Gastrointestinal autonomic nerve tumor ; Electron microscopy ; Immunohistochemistry ; Gastrointestinal tract
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Sixteen gastrointestinal stromal tumors (GISTs) were studied by immunohistochemical analysis and an ultrastructural procedure. The tumor locations were as follows: esophagus (2), stomach (7), small intestine (3), and large intestine (4). Four of the lesions were classified as malignant, 2 as borderline, and 10 as benign. On the basis of the immunohistochemical analysis, the tumors were classified as follows: 1 as myogenic type, 2 as Schwann cell type, 8 as Cajal cell type (including 2 gastrointestinal autonomic nerve tumors, GANTs), and 5 as mixed-cell type. In each subtype the phenotype was compared to the ultrastructural findings. Myogenic and Schwann cell type revealed ultrastructurally smooth muscle differentiation and schwannian tumor. All 8 tumors of the Cajal cell type revealed interdigitating cytoplasmic processes with occasional clusters of filopodia. Two tumors were subdivided as GANT. Five tumors of mixed-cell type were composed of a mixture of cells with variable myogenic features or variable neural differentiation. We confirmed in this study that immunohistochemical analysis reflected electron microscopic findings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050005
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  • 24
    Electronic Resource
    Electronic Resource
    Ultrastructural and immunohistochemical study of small cell neuroendocrine carcinoma of the parotid gland (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 122-126 
    Details
    ISSN: 1437-773X
    Keywords: Key words Small cell neuroendocrine carcinoma ; Parotid gland ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A case of small cell neuroendocrine carcinoma of the parotid gland is presented with immunohistochemical and electron microscopic studies. Small cell neuroendocrine carcinoma is extremely rare and is often difficult to distinguish from malignant lymphoma, adenoid cystic carcinoma, and undifferentiated carcinoma. Under light microscopy, the tumor cells consisted of solid sheets and nests of small tumor cells. Immunohistochemically, they were positive for KL-1 and EMA, and focally positive for NSE and synaptophysin. Observation using an electron microscope showed membrane-bound neuroendocrine granules in some tumor cells. Histological evaluation indicated that the present case was small cell carcinoma of the parotid gland, showing a neuroendocrine variety.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050018
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  • 25
    Electronic Resource
    Electronic Resource
    Reduction of cytochemical ecto-ATPase activities in keratin 8-deficient FVB/N mouse livers (1999)
    Springer
    Medical electron microscopy 32 (1999), S. 209-212 
    Details
    ISSN: 1437-773X
    Keywords: Key words Keratin ; Bile canaliculi ; Ecto-ATPase ; Transgenic mice ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Keratin 8 (K8) and keratin 18 are the intermediate filament proteins that are expressed in hepatocytes. A K8-deficient FVB/N mouse is a unique animal model for assessing the contribution of keratin intermediate filaments (IFs) to the structural and functional integrity of hepatocytes. Hepatocytes from homozygous (−/−) K8-deficient mice manifest a reduced bile acid secretion and an increased fragility to mechanical stress and hepatotoxic drugs. Hepatocytes from heterozygous (+/−) mice are more susceptible to drug-induced injury. Immunofluorescent microscopy revealed that hepatocytes from (+/−) mice maintained K8 IFs and F-actin that are similar to those in wild-type (+/+) mouse hepatocytes. In (−/−) mouse hepatocytes, K8 protein was negative and F-actin presented a coarse and irregular pattern. Ecto-ATPase, detected by enzyme histochemistry and observed by electron microscopy, was reduced in the bile canaliculi of both (+/−) and (−/−) mouse livers, in comparison with that of (+/+) mouse livers. These results reveal for the first time different microscopical findings regarding the livers of these three genotypes. They also suggest that the reduction of ecto-ATPase plays a role in the increased fragility of (+/−) and (−/−) mouse livers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950050004
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  • 26
    Electronic Resource
    Electronic Resource
    Extranodal follicular dendritic cell tumour of the nasopharynx (1998)
    Springer
    Virchows Archiv 432 (1998), S. 293-298 
    Details
    ISSN: 1432-2307
    Keywords: Key words Follicular dendritic cell tumour ; Nasopharynx ; Immunohistochemistry ; Electron microscopy ; PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We report the first case of an extranodal follicular dendritic cell (FDC) tumour localized in the nasopharynx of a 44-year-old male patient. The tumour cells were characterized immunohistochemically by strong expression of CD21, HLA-DR and vimentin and focal expression of CD68 and cytokeratin. Electron microscopic examination revealed desmosomal cell junctions between adjacent cell processes. Molecular genetic analysis using polymerase chain reaction (PCR) showed germline configuration of immunoglobulin and T-cell receptor genes. Epstein-Barr virus (EBV) genomes were detectable by PCR. After complete surgical tumour removal and radiotherapy the patient is disease-free 20 months after the initial diagnosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050168
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  • 27
    Electronic Resource
    Electronic Resource
    Cutaneous nerves in atopic dermatitis (1998)
    Springer
    Virchows Archiv 432 (1998), S. 363-370 
    Details
    ISSN: 1432-2307
    Keywords: Key words Atopic dermatitis ; Pruritus ; Cutaneous nerve ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Although pruritus is the cardinal symptom of atopic dermatitis, its mechanism is not well understood. Free nerve endings in the skin are involved in pruritus as itching receptors. We studied the cutaneous nerve fibres in lichenified lesions of 16 patients with adult atopic dermatitis. On immunohistochemistry, fibres immunoreactive for neurofilament, neuron-specific enolase, and protein gene product 9.5 were observed in the papillary dermis and dermoepidermal junctions as well as in the epidermis. In these areas, no fibres stained positively for substance P, neuropeptide Y, vasoactive intestinal peptide, beta endorphin, somatostatin or serotonin. On electron microscopy, the ultrastructure of subepidermal and intraepidermal free nerve endings appeared to be essentially normal. However, the distribution density of the cutaneous nerve fibres was much higher than in normal controls, and the diameter of these fibres was much larger, because of the large number of axons in each nerve fibre. Degranulation of mast cells was not seen. These findings suggest that pruritus in lichenified atopic skin is probably not caused by damage to the cutaneous free nerve endings. In such lesions, the number of the cutaneous free nerve endings is greatly increased, but they may have a normal function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050179
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  • 28
    Electronic Resource
    Electronic Resource
    Cell surface and nuclear changes during TNF-α-induced apoptosis in WEHI 164 murine fibrosarcoma cells (1998)
    Springer
    Virchows Archiv 433 (1998), S. 75-83 
    Details
    ISSN: 1432-2307
    Keywords: Key words Apoptosis ; Cell surface ; Cell nucleus ; Blebs ; TNF-α ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Tumour necrosis factor (TNF)-α-induced apoptosis is associated with several nuclear and cell surface alterations, in particular with the condensation of chromatin and the fragmentation of the cell nucleus, formation of blebs on the cell surface and breakdown of the plasma membrane. However, there is little information about the relationship between the cell surface alterations and the nuclear changes during apoptosis. To study this, cultured WEHI cells were exposed to TNF-α over different time periods. The cytological changes were studied using a correlative approach, which allowed observation of the same cell consecutively under light, scanning and transmission electron microscopy. The earliest sign of cell alteration was a reduction of the number of microvilli after 15 min of TNF-α exposure. This reaction was reversible (reappearance of microvilli) and took place during the first hour, in which neither nuclear alterations nor plasma membrane breakdown were observed. The changes in the nucleus began with condensation of chromatin after approximately 1 h of TNF-α-exposure. After 4–5 h the microvilli disappeared again, particularly in areas where the formation of blebs (blebbing) was observed. Strikingly, cell surface alterations (bleb formation) were detected only in those cells that presented with condensed chromatin, and not in cells with a normal chromatin pattern, proving at least a close correlation between nuclear and cell surface changes during the process of apoptosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050219
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  • 29
    Electronic Resource
    Electronic Resource
    In vivo diagnosis of Kufs’ disease by extracerebral biopsies (1998)
    Springer
    Acta neuropathologica 96 (1998), S. 102-108 
    Details
    ISSN: 1432-0533
    Keywords: Key words Adult ceroid lipofuscinosis ; Kufs’ disease ; Electron microscopy ; Extracerebral biopsies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In almost all of the earlier reported cases of Kufs’ disease, the adult form of ceroid lipofuscinosis, the diagnosis was ascertained by cerebral tissue examination, while peripheral biopsy examination revealed an apparent poor diffusion of specific lipofuscinic deposits, the finger print profiles (FPs). We report the ultrastructural data from skin, muscle and rectal biopsy specimens from two siblings, both still living, who present clinical features of Kufs’ disease. We observed the presence of FPs in locations that differ from the previous classic reports. Our results emphasize the value of extracerebral biopsies for the diagnosis of Kufs’ disease in vivo, and suggest some physiopathological assumptions based on vascular wall involvement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050866
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  • 30
    Electronic Resource
    Electronic Resource
    Hypoglycaemic neuropathy in BB/Wor rats treated with insulin implants: electron microscopic observations (1998)
    Springer
    Acta neuropathologica 96 (1998), S. 151-156 
    Details
    ISSN: 1432-0533
    Keywords: Key words Neuropathy ; Hypoglycemia ; Insulin ; implant ; Rat ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Insulin-dependent diabetes mellitus is a chronic metabolic disease that causes long-term secondary complications such as neuropathy. The occurrence of diabetic neuropathy has generally been thought of as being associated with hyperglycaemia. However, in a previous light microscopic examination of plantar nerves in diabetic BB/Wor rats treated with insulin implants we found that eu-/hyperglycaemic rats present a normal picture, whereas eu-/hypoglycaemic rats show severe changes. The aim of the present work is to supplement our previous light microscopic report with electron microsocpic data from the lateral plantar nerve of normal, eu-/hyperglycaemic and eu-/hypoglycaemic BB/Wor rats. Under the electron microscope lateral plantar nerves collected from eu-/hyperglycaemic rats presented a qualitatively normal picture. In addition, the fibre numbers and the size distribution of the myelinated fibres were normal. In contrast, specimens from eu-/hypoglycaemic BB/Wor rats showed severe qualitative changes, interpreted as signs of axonal de- and regeneration. The total number of axons was somewhat subnormal and the sizes of the myelinated fibres were strongly shifted towards smaller diameters. These data confirm our previous light microscopic observations. We conclude that eu-/hypoglycaemic BB/Wor rats treated with insulin implants, but not similarly treated eu-/hyperglycaemic animals, develop a neuropathy in their plantar nerves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050875
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  • 31
    Electronic Resource
    Electronic Resource
    The innervation of the synovium of the knee joint in the guinea pig: an immunohistochemical and ultrastructural study (1998)
    Springer
    Anatomy and embryology 197 (1998), S. 293-303 
    Details
    ISSN: 1432-0568
    Keywords: Key words Sensory neurons ; Autonomic neurons ; Neuropeptides ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The innervation of the knee joint synovial membrane of the guinea pig, i.e., the synoviocyte layer, the subjacent connective tissue and the connective tissue region beneath, was analyzed with immunohistofluorescence and electron microscopy. A screening of the innervation with antibodies against the general axon marker – protein gene product (PGP) 9,5 – revealed the presence of nerve fibers distributed in various regions of the knee joint synovial membrane. Confirmating previous studies, some of these nerve fibers stained with antibodies to tyrosine hydroxylase (TH), neuropeptide Y (NPY), substance P (SP), calcitonin gene-related peptide (CGRP), and vasoactive intestinal polypeptide (VIP). In addition, dynorphin (DYN)-containing fibers were detected, which have not been reported previously in normal joints. In general, the immunoreactive fibers were observed close to the synoviocytes and at blood vessels. Fibers with colocalization of NPY- and TH-like immunoreactivities (LIs), as well as of DYN- and TH-LIs were demonstrated. In the electron microscope, bundles of unmyelinated fibers as well as single fibers were found in the connective tissue region below the synoviocytes. Varicose parts of the nerve fibers contained mainly small, clear vesicles. Small and large dense-cored vesicles were also seen, but less frequently. Denser portions of the plasma membranes of some axons were observed in these regions, facing the extracellular space. Myelinated fibers were also observed in some nerve bundles. These findings emphasize the complex innervation of the synovial membrane, with nerve fibers containing a host of neuroactive substances. Altogether, these fibers are probably involved in many functions such as vasoregulation and control of synovial secretion in addition to being a source of mediators in joint inflammation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050139
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  • 32
    Electronic Resource
    Electronic Resource
    Intravenous injection of guanylin induces mucus secretion from goblet cells in rat duodenal crypts (1998)
    Springer
    Anatomy and embryology 197 (1998), S. 359-367 
    Details
    ISSN: 1432-0568
    Keywords: Key words Guanylin ; Mucus secretion ; Goblet cells ; Small intestine ; Edema ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Guanylin, structurally related to the heat-stable enterotoxin of E. coli, is a 15-amino-acid peptide isolated from rat small intestine. We investigated the morphological effects of an intravenous injection of rat and human guanylin upon the rat intestine. Various doses of rat guanylin were injected intravenously in anesthetized rats. After 5, 10 and 30 min, rats were killed by intracardiac perfusion with aldehyde fixative, and specimens of the intestine were then prepared for light and electron microscopy. Intravenously injected rat guanylin rapidly induced mucus secretion from crypt goblet cells in the duodenum. About half of the crypt goblet cells secreted mucous granules by compound exocytosis within 5 min. The villus goblet cells, in contrast, were not sensitive to guanylin. Goblet cells in the jejunum were less responsive than those in the duodenum. This secretory response was rare in the ileum and colon. Human guanylin produced similar results. The mucus secretion induced by guanylin was inhibited by a prior-injection of atropine, but not hexamethonium. Moreover, guanylin induced intense edema in the mucosa and submucosa of the small intestine 5 min after the injection, which disappeared after 30 min. A prior-injection of atropine did not block the appearance of edema. In conclusion, the intravenous injection of guanylin induces two phenomena related to water movement: (1) compound exocytosis of mucous granules from crypt goblet cells in the rat duodenum and jejunum; (2) perineural, inter-epithelial and intra-epithelial edema in the rat small intestine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050146
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  • 33
    Electronic Resource
    Electronic Resource
    Histopathological and ultrastructural features of feline hereditary cerebellar cortical atrophy: a novel animal model of human spinocerebellar degeneration (1998)
    Springer
    Acta neuropathologica 96 (1998), S. 379-387 
    Details
    ISSN: 1432-0533
    Keywords: Key words Cat ; Spinocerebellar degeneration ; Purkinje cell ; Distal dendrite ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Human spinocerebellar degeneration is one of the intractable diseases. We studied the detailed neuropathology of cats with hereditary cerebellar degeneration obtained from the experimental breeding. The findings included almost total loss of Purkinje cells with an increase in Bergmann’s glia in the cerebellar hemisphere, preservation of some Purkinje cells in the vermis and moderate neuronal depletion of the olive nucleus. Cerebellar and pontine nuclei were normal. The cerebrum and spinal cord as well as the peripheral nervous system appeared normal. Electron microscopic examination revealed swelling of the distal dendrites of Purkinje cells in the less-affected nodule of the vermis, and clusters of presynaptic boutons without any synaptic contact in the severely affected folia where Purkinje cell bodies and dendrites disappeared. Prolonged existence of presynapses in the molecular and Purkinje cell layers was confirmed by positive immunoreactivity to anti-synaptophysin. Quantitative analysis using electron microscopy demonstrated an apparent increase in the density and mean size of presynapses in the molecular layer of the severely affected folia. These findings indicate that degeneration of Purkinje cells started at the most distal part of the dendrite in this animal model of cerebellar degeneration, and that presynapses, axon terminals of the granular cells and basket cells can exist for a long time even after complete degeneration of the Purkinje cells. Further investigation of this novel animal model may promote a better understanding of pathogenesis of human hereditary cerebellar degeneration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050908
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  • 34
    Electronic Resource
    Electronic Resource
    Changes in synaptology of adult cat spinal α-motoneurons after axotomy (1998)
    Springer
    Experimental brain research 118 (1998), S. 1-13 
    Details
    ISSN: 1432-1106
    Keywords: Key words Nerve injury ; Retrograde reaction ; Spinal cord ; Electron microscopy ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this electron-microscopic study was to analyze the distribution of synaptic contacts on the cell bodies and dendrites of permanently axotomized adult cat spinal α-motoneurons. Following transection and ligation of the medial gastrocnemius nerve, the synaptic covering of the cell bodies and three different dendritic compartments of homonymous α-motoneurons was analyzed quantitatively at 3, 6, and 12 weeks postoperatively. The synaptic boutons were classified according to their size and the shape of their synaptic vesicles. On the soma, a transient increase in the number of boutons was noted at 3 weeks and 6 weeks postoperatively, while after 12 weeks the bouton number had decreased to half of its normal value. The transient increase was mainly due to an increase in the number of F-type boutons. At 12 weeks postoperatively, the synaptic covering was reduced by 83% on the soma and by 57% on the proximal dendrites. In the distal dendritic regions, the values for synaptic covering remained largely unchanged. In summary, axotomized motoneurons exhibit a reduction in synaptic covering which is maximal on the cell body and becomes less pronounced centrifugally along the dendrites. However, if also taking into account the loss of distal dendritic branches that occurs in axotomized motoneurons, the total loss of boutons is several times larger in the dendrites than on the soma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050249
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  • 35
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    Electronic Resource
    Differential localisation of the metabotropic glutamate receptor mGluR1a and the ionotropic glutamate receptor GluR2/3 in neurons of the human cerebral cortex (1998)
    Springer
    Experimental brain research 119 (1998), S. 367-374 
    Details
    ISSN: 1432-1106
    Keywords: Key words Glutamate receptors ; Immunocytochemistry ; Electron microscopy ; Human cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Specimens of human cerebral cortex were obtained during neurosurgical operations and studied by immunocytochemistry and electron microscopy, using antibodies to the metabotropic glutamate receptor subunit mGluR1a and the ionotropic glutamate receptor GluR2/3. A small number of non-pyramidal neuronal cell bodies were labelled for mGluR1a. Double immunolabelling with mGluR1a and GluR2/3 showed that most pyramidal cell bodies were labelled for GluR2/3 but not for mGluR1a. Despite the non-colocalisation of these two receptor subtypes in cell bodies, however, many dendrites and dendritic spines were double-labelled for mGluR1a and GluR2/3 at electron microscopy. As there is evidence that most neurons positive for GluR2/3 are pyramidal cells, this suggests that mGluR1a is present in dendrites of pyramidal neurons, despite absent or low levels of immunoreactivity in their cell bodies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050352
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  • 36
    Electronic Resource
    Electronic Resource
    Morphological and physical characterization of the capsular layer of Vibrio cholerae O139 (1998)
    Springer
    Archives of microbiology 170 (1998), S. 339-344 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsV. cholerae O139 ; Lipopolysaccharide ; Electron microscopy ; Freeze-substitution technique ; Capsule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The morphological and physical characteristics of the capsule of Vibrio cholerae O139 were examined. An electron microscopic study using the freeze-substitution technique showed that all of the V. cholerae strains of the O139 serogroup examined have a very thin fibrous layer on the outside of the outer membrane. In contrast, the mutants of strain O139, strain MO10T4 (which lacks capsule synthesis), and strain Bengal-2R1 (which fails to synthesize both the capsule and the O-antigen of lipopolysaccharide) were all found to have lost the surface layer. In addition, the capsule layer could also not be observed on the surface of V. cholerae strain O1. To determine the biological characteristics of the capsule of strains of the O139 serogroup, we investigated the serum killing activity and bacterial phagocytosis by polymorphonuclear leukocytes. The O139 strains were more resistant to the serum killing activity than were the V. cholerae O1 strain and the O139 mutant strains, thus suggesting that the existence of the capsule gave a serum-resistant character to the O139 strains. The surface character of the O139 strains had the same hydrophobic character as did that of the O139 mutant strains and the O1 strain. In addition, all the V. cholerae O1 and O139 strains examined, including the mutant strains, were effectively ingested by the human polymorphonuclear leukocytes. The number of ingested bacteria was not significantly different among the strains, and the ingestion of the acapsular O139 mutants thus showed that the capsule does not play an antiphagocytic role. These data suggest that the capsule of V. cholerae O139 has a physiological function different from that of the ordinal hydrophilic capsule that is found in invasive bacteria such as Klebsiella pneumoniae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050651
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  • 37
    Electronic Resource
    Electronic Resource
    Phylogenetic affiliation and ultrastructure of uncultured magnetic bacteria with unusually large magnetosomes (1998)
    Springer
    Archives of microbiology 169 (1998), S. 136-147 
    Details
    ISSN: 1432-072X
    Keywords: Key words Magnetic bacteria ; Biomineralization ; Magnetite ; 16S rRNA ; In situ hybridization ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Natural enrichments of magnetic bacteria from the Itaipu lagoon near Rio de Janeiro were dominated by coccoid-to-ovoid morphotypes that produced unusually large magnetosomes. To determine the phylogenetic position of these unusual microorganisms, 16S rRNA genes were retrieved from bacteria magnetically separated from sediment of the Itaipu lagoon by in vitro amplification and cloning of PCR products into a plasmid vector. Partial sequencing of the obtained clones revealed two clusters of closely related sequences affiliated to a distinct lineage consisting exclusively of magnetic bacteria within the α-subclass of Proteobacteria. For a detailed phylogenetic analysis, several almost complete sequences of the 16S rRNA genes were determined. One representative clone of each cluster provided a PCR template for the in vitro transcription of group-specific polynucleotide probes complementary to a variable region of the 16S rRNA molecule. At least three different morphotypes of magnetic bacteria were reliably identified by post-embedding hybridization of ultra-thin sections. Electron microscopic analyses of hybridized cells enabled for the first time a detailed description of the morphological variety and ultrastructure of phylogenetically identified, uncultured magnetic bacteria. Two distinct coccoid bacteria were identified by the transcript probe complementary to the 16S rRNA sequence mabrj12, whereas the probe complementary to the sequence mabrj58 allowed the identification of an ovoid morphotype that displayed magnetosomes with the largest volumes observed to date.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050553
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  • 38
    Electronic Resource
    Electronic Resource
    Cell biology, clinicopathological profile, and classification of gastro-enteropancreatic endocrine tumors (1998)
    Springer
    Journal of molecular medicine 76 (1998), S. 413-420 
    Details
    ISSN: 1432-1440
    Keywords: Key words Endocrine tumors ; Histochemistry ; Electron microscopy ; Pathology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Recent developments in the field of endocrine cell biology and pathology at both morphological and molecular levels are briefly outlined and discussed as a basis for endocrine tumor characterization. The main tools available for identifying the endocrine nature of the tumors, their pathogenetic interpretation, and experimental reproduction with special emphasis on tumor antecedents are reported. Based on this, classifications of endocrine tumors of the pancreas and gastrointestinal tract are developed, covering most clinical (hyperfunctional syndromes included), pathological, and biological patterns, with special emphasis on tumor prognosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001090050233
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  • 39
    Electronic Resource
    Electronic Resource
    Interaction of the Escherichia coli DnaA protein with bacteriophage k DNA (1998)
    Springer
    Molecular genetics and genomics 259 (1998), S. 679-688 
    Details
    ISSN: 1617-4623
    Keywords: Key words Bacteriophage λ ; DnaA-DNA interactions ; Electron microscopy ; DNA-protein complexes ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Interaction of the Escherichia coli DnaA (replication initiator) protein with restriction fragments of phage λ DNA demonstrated differential binding of DnaA along the whole λ DNA. Interaction of DnaA with the λ replication region (from the promoter p R to the origin of replication, oriλ) demonstrated a strong binding of DnaA to the region around the p o promoter where synthesis of a short antisense oop RNA is initiated. The four sequences protected by DnaA (two 9mers and two 5mers) are not related even to a relaxed DnaA box. The pattern of protection of these four sequences and the location of three DNase I hypersensitive sites in the λ DNA r strand, together with results of mobility shift assays and electron microscopy studies, may indicate an interaction involving DnaA monomers bound to different DNA positions on one side of the helix and the formation of higher-order nucleoprotein structures. Therefore, it is tempting to suggest that DnaA, in addition to its activity in regulation of replication and transcription, could be considered as a factor which structures certain chromosomal regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004380050863
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  • 40
    Electronic Resource
    Electronic Resource
    Virus assembly inHincksia hincksiae (Ectocarpales, Phaeophyceae) An electron and fluorescence microscopic study (1998)
    Springer
    Protoplasma 203 (1998), S. 153-167 
    Details
    ISSN: 1615-6102
    Keywords: Algae ; Virus assembly ; DAPI staining ; Electron microscopy ; Hincksia hincksiae ; Immunofluorescence ; Marine double-stranded DNA virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The filamentous brown algaHincksia hincksiae can be infected by a large icosahedral double-stranded DNA virus (HincV-1). The virus shows extended latency and is replicated only in cells homologous to sporangia. Virus formation was studied by transmission electron microscopy, DAPI staining, and β-tubulin immunofluorescence. Inhibition of cytokineses results in multinucleate cells, which are the first indication of virus replication in productive cells; the microtubular cytoskeleton does not seem to be affected by the virus. Replication of viral DNA begins in the nuclei, which increase in size and eventually disintegrate. Virus assembly takes place in a mixed nucleo-/cytoplasm. Capsids bud from cisternae, which are interpreted as modified endoplasmic reticulum aggregated to virus assembly centres. The internal membranous component of the virus is thus derived from the endoplasmic reticulum. The particles are empty (electron translucent) when assembled, and the nucleoprotein core seems to be packaged subsequently through an opening in the capsid. A number of fine structural features not previously reported from brown algae and related to virus formation are described. Our results on Hincksia hincksiae virus are compared with observations made on various other icosahedral DNA viruses infecting eukaryotic algae and animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279472
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  • 41
    Electronic Resource
    Electronic Resource
    Electron and X-ray microscopic analyses of reaggregated materials obtained after fractionation of dissolved sporopollenin (1998)
    Springer
    Protoplasma 204 (1998), S. 13-21 
    Details
    ISSN: 1615-6102
    Keywords: Sporopollenin ; Solubilisation ; 2-Aminoethanol ; Reaggregation ; Electron microscopy ; X-ray microscopy ; Thypha angustifolia L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Exines fromTypha angustifolia L. pollen were dissolved in hot 2-aminoethanol. The solubilisate was successively fractionated and reaggregated via a dialysis cascade with dialysis tubings of different exclusion volumina. Four fractions of reaggregated material with different molecular mass were obtained. Fraction 1 with a molecular mass above 25,000 Da, fraction 2 with a molecular mass between 10,000–25,000 Da, fraction 3 with a molecular mass between 5,000–10,000 Da, and fraction 4 of a molecular mass lower than 5,000 Da. The fractions were comparatively analysed by scanning and transmission electron microscopy and X-ray microscopy. The material of the fractions with a molecular mass above 10,000 Da exhibit high congruence to the initial material. Analysis of the reaggregated material with the lowest molecular mass revealed special distinct substructures which in form and size showed high similarities to substructures of exines described in literature. In detail, spherical substructures consisting of an electron-dense core surrounded by an electron-transparent corona and in addition elongated substructures with a distinctive surface sculpture were detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01282289
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  • 42
    Electronic Resource
    Electronic Resource
    Callose deposition and breakdown, followed by phytomelan synthesis in the seed coat ofGasteria verrucosa (Mill.) H. Duval (1998)
    Springer
    Protoplasma 201 (1998), S. 221-230 
    Details
    ISSN: 1615-6102
    Keywords: Callose ; Electron microscopy ; Gasteria verrucosa ; Phenolics ; Phytomelan ; Seed coat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the seed coat ofGasteria verrucosa the deposition of phytomelan takes place during seed development in three stages. Phytomelan is a black cell wall material which is chemically very inert. First the radial walls and part of the transverse cell wall of the outer epidermis of the outer integument become thickened by exocytosis of dictyosome vesicles. Callose is deposited at the tangential plasma membrane against those walls. After the callose deposition about two thirds of the original cell volume is filled with callose. During the second stage the callose is broken down, probably into glucose monomers or small polymers. At the same time cellulose is deposited at the outer tangential plasma membrane, forming a wall between the dissolving callose and the plasma membrane. In the third phase small granules appear in the solution of dissolved callose. which grow out and finally fuse to form a block of phytomelan, consisting of spherical 15-nm units. Remarkable is the function of the callose: it determines the size of the phytomelan block, and it probably functions as carbohydrate source for the phytomelan synthesis and/or for the cellulose inner layer. In this study transmission electron microscopy and cryo scanning electron microscopy are used to study the three developmental stages of the formation of the phytomelan layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01287418
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  • 43
    Electronic Resource
    Electronic Resource
    Distribution and submicroscopic immunogold localization of cellular prion protein (PrPc) in extracerebral tissues (1998)
    Springer
    Cell & tissue research 292 (1998), S. 77-84 
    Details
    ISSN: 1432-0878
    Keywords: Key words Prion protein (PrPc) ; Electron microscopy ; Secretory granules ; Membrane ; Extracerebral tissues ; Hamster ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  In transmissible spongiform encephalopathies (TSE), such as scrapie in animals and Creutzfeldt-Jakob disease in humans, the central event is the conversion of a host-encoded amyloidogenic protein (PrPc) into an abnormal isoform (PrPsc) that accumulates as amyloid in TSE brain. PrPc is a membrane sialoglycoprotein synthesized in the central nervous system and elsewhere. We have examined the ultrastructural localization of PrPc in numerous hamster and some human extracerebral tissues, by means of a post-embedding electron-microscopic method combined with immunogold labeling. In stomach, intestine, lung, and kidney from hamsters, and in stomach, kidney, and spleen from humans, immunogold labeling specific for PrPc is observed on various cellular substructures related to secretory pathways: Golgi apparatus, secretory globules, and plasma membrane. In mucous epithelial cells of stomach and intestine, PrPc appears to be concentrated in secretory globules, suggesting a role for PrPc in the secretory function of the digestive tract. The secretory aspect of PrPc may be a key to understanding the physiopathological mechanisms underlying TSE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051036
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  • 44
    Electronic Resource
    Electronic Resource
    Regeneration of epithelial cells of the maxillary sinus mucosa in chronic sinusitis (1998)
    Springer
    Medical molecular morphology 31 (1998), S. 10-15 
    Details
    ISSN: 1860-1499
    Keywords: Sinusitis ; PCNA (proliferative cell nuclear antigen) ; Electron microscopy ; Regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The maxillary mucosae of chronic sinusitis patients were observed by transmission and scanning electron microscopy. Although the epithelium was severely damaged by the chronic inflammation and the ciliated cells and goblet cells were degraded and had peeled off, most of the basal cells survived at the surface of the mucosa. The surviving basal cells extended their cytoplasmic processes toward each other and finally covered the bare surface of the mucosa. Cells having a few cilia and many microvilli were occasionally observed. Immunohistochemistry for PCNA (proliferating cell nuclear antigen) was also performed. The nuclei of many basal cells in the nonciliated area and those of a few ciliated cells were positive for PCNA. These findings suggest that the maxillary mucosa of chronic sinusitis has the ability to regenerate and that basal cells play the role of precursors to ciliated cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01547943
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  • 45
    Electronic Resource
    Electronic Resource
    Fine structure and cytochemistry of human leukemia HL-60 cells during etoposide-induced apoptosis (1998)
    Springer
    Medical molecular morphology 31 (1998), S. 16-23 
    Details
    ISSN: 1860-1499
    Keywords: Apoptosis ; Electron microscopy ; Leukemia cell ; DNA ; Cytoplasm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To examine the morphological changes of HL-60 cells undergoing apoptosis, we induced apoptosis by etoposide treatment, and compared the findings obtained with an electron microscopic cytochemical method with those obtained with in situ end-labeling (ISEL) of DNA and a DNA fragmentation assay. Apoptotic cells were detected by ISEL of DNA 1h before the ladder formation in the DNA fragmetation assay, and an accumulation of DNA was observed simultaneously around the nucleoli and nuclear membrane by DNA-staining electron microscopy. These findings revealed that the apoptosis-related changes occurred in the DNA before the appearance of ladder formation. DNA staining with osmium ammine B revealed, at higher magnification, a rough fiber formation of DNA before apoptosis and an accumulation of small particles with the course of apoptosis. The number of primary granules stained for peroxidase in the cytoplasm decreased as apoptosis progressed. An examination by the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) method revealed in number after the induction of apoptosis. Thus, apoptosis-related changes were observed not only in the nucleus but also in the cytoplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01547944
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  • 46
    Electronic Resource
    Electronic Resource
    Ultrastructural study of biopsy specimens of acute fatty liver of pregnancy (1998)
    Springer
    Medical molecular morphology 31 (1998), S. 42-48 
    Details
    ISSN: 1860-1499
    Keywords: Acute fatty liver of pregnancy ; Disseminated intravascular coagulation ; Mitochondria ; Microvesicular fatty droplets ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Biopsy specimens obtained from the liver of a 32-year-old woman, diagnosed with acute fatty liver of pregnancy, were examined by light and electron microscopy. The patient had become pregnant after artificial insemination. At the 36th week of gestation, she suffered simultaneous fetal distress and liver dysfunction, and a cesarean operation was done immediately. Liver biopsies were performed on the 7th and 38th day after the cesarean operation. The first biopsy revealed enlarged hepatocytes in pericentral areas. Many transformed mitochondria with tubular cristae, which were often seen in steroid hormoneproducing cells and adrenal cortical cells, and microvesicular fatty droplets were detected in some swollen hepatocytes, as revealed by electron microscopy. At the second biopsy, almost all hepatocytes had recovered normal morphology as the result of appropriate treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01547948
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  • 47
    Electronic Resource
    Electronic Resource
    Delayed neuronal cell death and microglial cell reactivity in the CA1 region of the rat hippocampus in the cardiac arrest model (1998)
    Springer
    Medical molecular morphology 31 (1998), S. 85-93 
    Details
    ISSN: 1860-1499
    Keywords: Ischemia ; Delaved neuronal cell death ; Apoptosis ; Microglia ; Electron microscopy ; Rat ; Hippocampus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Morphological changes in the CA1 region of the hippocampus in the rat cardiac arrest model were studied with the in situ nick-end labeling (TUNEL) method and light and electron microscopy. The TUNEL-positive pyramidal cells first appeared on day 1, increased in number with time, and reached a peak at 7 days after recirculation. At the ultrastructural level, cell shrinkage, nuclear fragmentation, and an increased number of atuophagic vacuoles of the pyramidal cells were observed in the CA1 region. The brief ischemia activates the microglial cells in the CA1 region, and these cells were found to increase in number with time. The microglial cells were seen to adhere to degenerating pyramidal cells and to phagocytose the apoptotic neurons selectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01557785
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  • 48
    Electronic Resource
    Electronic Resource
    p53 expression in congenital experimental hydrocephalus induced by rat kidney antiserum (1998)
    Springer
    Medical molecular morphology 31 (1998), S. 121-127 
    Details
    ISSN: 1860-1499
    Keywords: Congenital hydrocephalus ; Antipregnant rat kidney serum ; p53 ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Congenital hydrocephalus was induced by intraperitoneal administration of antipregnant rat kidney serum (APRKS) into rats at 9 days of pregnancy. To clarify a correlation between the oncogenes and expression of hydrocephalus, immunostaining of the fetal rat nervous system for p53 was carried out using Ab-1, a pantropic antirat p53 antibody, and Ab-3, raised against a mutant form of rat p53, Ab-1 staining was observed in cells of the neural plate of the fetus, the yolk sac, and the placenta. Because no staining occurred with Ab-3, it was likely that the p53 induced by antiserum injection was the wild-type protein. This result indicated that p53 may represent a reparative reaction to DNA damage from the APRKS; also, when DNA is irreparably damaged, p53 could induce apoptosis by favoring transcription of a gene encoding an inducet of apoptosis. Insufficient apoptosis, on the other hand, may induce failure of fetal development, contributing in particular to congenital hydrocephalus and other central nervous system anomalies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01553779
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  • 49
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    Electronic Resource
    An ultrastructural study of subungual exostosis, with special reference to intranuclear inclusions (1998)
    Springer
    Medical molecular morphology 31 (1998), S. 142-146 
    Details
    ISSN: 1860-1499
    Keywords: Subungual exostosis ; Bone formation ; Intranuclear inclusion ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 12-year-old Japanese boy noticed a red nodule on the distal portion of his right great toe about 2 months before entering our clinic. There was evidence of traumatic injury and infection before the appearance of the nodule. Histological examination showed the subcutaneous localization of bony spicules lined by osteoblasts. Haversian canals, which contained blood vessels and connective tissue, were also seen. Electron microscopic examination revealed normal bone structure, but, interestingly, mesenchymal cells that were localized around the tumor had intranuclear inclusions composed of filamentous bundles. From these findings, this case was diagnosed as subungual exostosis. It is suggested that the appearance of intranuclear inclusions, reported here for the first time, is related to the pathogenesis of subungual exostosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01553782
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  • 50
    Electronic Resource
    Electronic Resource
    Ultrastructural and biochemical studies on the intestinal absorption of a medium-chain triglyceride (MCT), tricaprylin (1998)
    Springer
    Medical molecular morphology 31 (1998), S. 193-199 
    Details
    ISSN: 1860-1499
    Keywords: Electron microscopy ; Medium-chain triglyceride ; Intestinal absorption ; Lacteal ; Very low density lipoprotein (VLDL)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The intestinal absorption of a medium-chain triglyceride (MCT) was studied by electron microscopy and biochemical analysis. In jejunal absorptive cells of rats fed tricaprylin, the smooth endoplasmic reticulum in the apical cytoplasm appeared to increase in number and contained one or two particles about 40–80 nm in diameter that were less electron dense and similar in size and profile to very low density lipoprotein. Similar particles were also observed packed in the dilated Golgi sacs and in the extended intercellular spaces. These particles were remarkably increased in number as compared with those in fasted rats. Biochemical analysis of lymph from the main intestinal lymph duct showed that caprylate was apparently demonstrated only in the lymph of rats given tricaprylin at the maximum rate 3h after oral administration. The study strongly suggests that medium-chain triglyceride is at least in part transported via lacteal, possibly in the form of very low density lipoprotein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01545701
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  • 51
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    Electronic Resource
    Malignant mesenchymal tumors of the ovary in three cases: Histology, immunohistochemistry, and ultrastructural observations (1998)
    Springer
    Medical molecular morphology 31 (1998), S. 207-215 
    Details
    ISSN: 1860-1499
    Keywords: Ovary ; Sarcoma ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Primary ovarian sarcoma is a rare neoplasm. The diagnosis sometimes becomes difficult by light microscopic examination alone because of the rarity and heterogeneity of these tumors. Immunohistochemical and ultrastructural studies are very useful for diagnosis. Here, we describe two cases of ovarian sarcomas: fibrosarcoma and leiomyosarcoma, and a case of carcinosarcoma (homologous malignant mixed müllerian tumor). In addition to histological findings, immunohistochemical and ultrastructural observation was undertaken to make a final diagnosis. Clinical outcome was variable in the three cases. It was unlikely to be related to the disease stage or treatment, such as surgical excision or anticancer drugs, whereas the mitotic index may be an important prognostic indicator in ovarian sarcomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01545703
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  • 52
    Electronic Resource
    Electronic Resource
    Primary linitis plastica type carcinoma of the small intestine: An immunohistochemical and electron microscopic study (1998)
    Springer
    Medical molecular morphology 31 (1998), S. 216-221 
    Details
    ISSN: 1860-1499
    Keywords: Small intestine ; Carcinoma ; Linitis plastica ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We examined a case of an 87-year-old man who had had a 1-month history of ileus of unknown cause. Postmortem examination revealed numerous foci of constriction and thickening throughout the small intestine, associated with perforation and panperitonitis. Histologically. diffuse infiltration of anaplastic atypical cells was found in the wall of almost the entire small intestine. The atypical cells were immunohistochemically positive for carcinoembryonic antigen and epithelial membrane antigen. In the electron microscopic examination, most of those cells had microvilli with filamentous core rootlets and terminal webs. There was no atypical cell infiltration in the stomach or large intestine. We concluded that this case was primary linitis plastica type carcinoma of the small intestine involving almost the entire small intestine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01545704
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  • 53
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    Electronic Resource
    Molecular imprinting technology: challenges and prospects for the future (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 195-209 
    Details
    ISSN: 0899-0042
    Keywords: molecular imprinting ; molecular recognition ; chirality ; chromatography ; catalysis ; biosensor ; immunoassay ; antibody mimic ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular imprinting is a technique for the fabrication of biomimetic polymeric recognition sites or “plastic antibodies/receptors” which is attracting rapidly increasing interest. By this technology, recognition matrices can be prepared which possess high substrate selectivity and specificity. In the development of this technology, several applications have been foreseen in which imprinted materials may be exchanged for natural recognition elements. Thus, molecularly imprinted polymers have been used as antibody/receptor binding mimics in immunoassay-type analyses, as enzyme mimics in catalytic applications and as recognition matrices in biosensors. The best developed application area for imprinted materials, though, has been as stationary phases for chromatography, in general, and chiral chromatography, in particular. This review seeks to highlight some of the more intriguing advantages of the technique as well as pointing out some of the difficulties encountered. The prospects for future development will also be considered. Chirality 10:195-209, 1998. © 1998 Wiley-Liss, Inc.
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    Separation of (R)- and (S)-tert-butyl 2-tert-butyl-4-methoxy-2,5-dihydro-1,3-imidazole-1-carboxylate (building block for amino acid synthesis) by preparative high performance liquid chromatography on a polysaccharide stationary phase (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 217-222 
    Details
    ISSN: 0899-0042
    Keywords: amylose ; 3,5-dimethylphenyl-carbamate ; polysaccharide phase ; tert-butyl 2-tert-butyl-4-methoxy-2,5-dihydro-1,3-imidazole-1-carboxylate; amino acid ester synthesis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparative separation of the enantiomers of the title compound, a versatile chiral building block for the synthesis of unnatural amino acid esters, by high performance liquid chromatography on a chiral stationary phase (CSP), is reported for the first time. The CSP consists of amylose-(3,5-dimethylphenyl-carbamate), which has been coated onto the surface of macroporous aminopropyl-functionalized silica gel. The effect of mobile phase composition and the amount of amylose derivative on the silica gel has been thoroughly investigated. Using 2-propanol as organic modifier in hexane as mobile phase, on a semi-preparative column (200 mm × 40 mm ID, containing 192 g of stationary phase) about 200 mg of the racemate was separated per injection. Running the equipment under automatic conditions with repetitive injection mode allowed for the separation of 30 g per day. Both enantiomers were obtained with enantiopurities 〉99.75:0.25. Chirality 10:217-222, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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    Species-dependent enantioselective pharmacokinetics of PNU-103017, a Pyrone HIV protease inhibitor (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 210-216 
    Details
    ISSN: 0899-0042
    Keywords: enantiospecific assay ; rat ; dog ; human ; enantiomer disposition ; HIV protease inhibitor ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: PNU-103017, 4-Cyano-N-(3-(cyclopropyl(5,6,7,8,9,10-hexahydro-4-hydroxy-2-oxo-2H-cycloocta(b) pyran-3-yl)methyl)phenyl)-benzenesulfonamide, is a selective HIV aspartyl protease inhibitor under evaluation as a potential oral treatment of Acquired Immunodeficiency Diseases. PNU-103017 is a racemic mixture of two enantiomers, designated PNU-103264 (R-) and PNU-103265 (S-). Stereoselective pharmacokinetics of the two enantiomers of PNU-103017 were observed in the dog, rat, and human after single and multiple dose administration of the racemate and were apparently species-dependent. Mean enantiomeric ratios of plasma concentrations (R-/S-) at each time point were greater than 1 in the dog, ranging from 1.22 to 3.06, but less than 1 in the rat and in the human, ranging from 0.44 to 0.80 and 0.23 to 0.73, respectively. A trend towards increased or decreased (farther from 1:1, R-/S-) enantiomeric ratio of plasma concentrations with time after each administration was also observed. The enantiomeric ratio remained unchanged after multiple dose administration in the rat, dog, and human although enzyme induction and increased plasma clearance were observed for both enantiomers. Chirality 10:210-216, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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    Chiral interaction and stochastic kinetics in stirred crystallization of amino acids (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 238-245 
    Details
    ISSN: 0899-0042
    Keywords: chiral selectivity ; amino acid crystallization ; molecular recognition ; stochastic kinetics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study of chirally selective interaction in the stirred crystallization of glutamic acid and lysine is presented. The crystallization of S-glutamic acid is influenced by the presence of S-lysine but not R-lysine. Crystal nuclei in stirred systems are produced due to secondary nucleation. Secondary nucleation is an autocatalytic process in which a crystal produces secondary nuclei due to fluid motion, and due to crystal stirrer and crystal-crystal collisions. As a result of this autocatalysis, small fluctuations in the nucleation rates are amplified and the kinetics show a marked stochastic behavior. We investigate the stochastic behavior in detail and propose a kinetic mechanism that explains both the increase and the statistical distribution of the crystallization times of S-glutamic acid due to the presence of S-Lysine. Chirality 10:238-245, 1998. © 1998 Wiley-Liss, Inc.
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    Enantiomers of thalidomide: blood distribution and the influence of serum albumin on chiral inversion and hydrolysis (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 223-228 
    Details
    ISSN: 0899-0042
    Keywords: thalidomide enantiomers ; in vitro kinetics ; blood distribution ; human serum albumin ; chiral inversion ; plasma protein binding ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aim of this investigation was to elucidate the distribution and reactions of the enantiomers of thalidomide at their main site of biotransformation in vivo, i.e., in human blood. Plasma protein binding, erythrocyte: plasma distribution, and the kinetics of chiral inversion and degradation in buffer, plasma, and solutions of human serum albumin (HSA) were studied by means of a stereospecific HPLC assay. The enantiomers of thalidomide were not extensively bound to blood or plasma components. The geometric mean plasma protein binding was 55% and 66%, respectively, for (+)-(R)- and (-)-(S)-thalidomide. The corresponding geometric mean blood:plasma concentration ratios were 0.86 and 0.95 (at a haematocrit of 0.37) and erythrocyte:plasma distributions were 0.58 and 0.87. The rates of inversion and hydrolysis of the enantiomers increased with pH over the range 7.0-7.5. HSA, and to a lesser extent human plasma, catalysed the chiral inversion, but not the degradation, of (+)-(R)- and (-)-(S)-thalidomide. The addition of capric acid or preincubation of HSA with acetylsalicylic acid or physostigmine impaired the catalysis to varying extents. Correction for distribution in blood enhances previously observed differences between the pharmacokinetics of the enantiomers in vivo. The findings also support the notion that chiral inversion in vivo takes place mainly in the circulation and in albumin-rich extravascular spaces while hydrolysis occurs more uniformly in the body. In addition, the chiral inversion and hydrolysis of thalidomide apparently occur by several different mechanisms. Chirality 10:223-228, 1998. © 1998 Wiley-Liss, Inc.
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    Mechanistic aspects of the biogenesis of rose oxide in Pelargonium graveolens L'Héritier (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 229-237 
    Details
    ISSN: 0899-0042
    Keywords: deuterium labelling ; menthocitronellol ; citronellol ; enantioselective multidimensional gas chromatography-mass spectrometry (enantio-MDGC-MS) ; dynamic headspace analysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mechanistic aspects of the biogenesis of the chiral monoterpenoid rose oxide in Pelargonium graveolens L'Héritier are investigated using deuterium-labelled precursors. After administration of the precursors using the cut-stem method, the dynamic headspace extracts of the plants are analysed using multidimensional gas chromatography-mass spectrometry (enantio-MDGC-MS). It is unequivocally shown that this plant is able to convert citronellol and menthocitronellol into cis-/trans-rose oxide. Menthocitronellol is converted into rose oxide with a clearly detectable enantiodiscrimination. These facts may be explained with the presence of an oxidase, which is able to oxidize citronellol and menthocitronellol in allylic position. A photooxygenation mechanism including singlet oxygen as the oxidizing agent is rather unlikely. Chirality 10:229-237, 1998. © 1998 Wiley-Liss, Inc.
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    Chloroperoxidase-induced asymmetric sulfoxidation of some conformationally restricted sulfides (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 246-252 
    Details
    ISSN: 0899-0042
    Keywords: sulfoxides ; chloroperoxidase ; asymmetric oxidation ; enantioselective ; episulfide ; gas chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Asymmetric sulfoxidation by means of a chloroperoxidase from Caldariomyces fumago and hydrogen peroxide as the oxygen source was studied for a series of sterically well-defined substrates. The stereochemistry of the sulfoxidation was the same for all substrates studied. While 2,3-dihydrobenzo[b]thiophene (1) is an excellent substrate (giving 99.5% yield and 99% e.e. of the (R)-sulfoxide), replacement of a methylene group by either a more sterically demanding group or a heteroatom caused a substantial decrease in reactivity or in reactivity as well as enantioselectivity. A further investigation of the lowered catalytic efficiency of chloroperoxidase with these substrates has been carried out in a series of competitive reactions. Thus, benzo[1,3]oxathiole (5) acted as a competitive inhibitor of the enzyme, whereas 1-thiochroman (2) and 1-thiochroman-4-one (3) were shown to be too sterically demanding to significantly compete for the active site. For the oxidation of 2, 3, and 5, it was found that in the low CPO concentration range the chemical yield after 60 min reaction time increased almost linearly with the amount of CPO used. The products from 2 and 3 could be obtained in over 80% yield with an e.e. exceeding 96%. Chloroperoxidase was also found to be an effective catalyst in the oxidation of labile episulfides, yielding the corresponding anti-sulfoxides quantitatively and giving 12% e.e. of (1R, 2R)-sulfoxide in the oxidation of propylene sulfide. Chirality 10:246-252, 1998. © 1998 Wiley-Liss, Inc.
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    1997 Chirality Medal (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 281-281 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
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    Circular dichroism of axially chiral methaqualone, 3-Aryl-2-mercapto- and 3-aryl-2-alkylthio-4(3H)-quinazolinones: conformational dependence of CD and assignment of absolute configuration (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 253-261 
    Details
    ISSN: 0899-0042
    Keywords: chiroptical properties ; Cotton effect ; atropisomerism ; quantum-mechanical calculation ; AM1 ; CNDO/S ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rotational strengths calculated on the basis of quantum-mechanically obtained minimum energy geometries were used to determine the absolute configurations of axially chiral 3-aryl-4(3H)-quinazolinones from the sign of the observed Cotton effects (CEs). For the spectral data, CNDO/S calculations were used; for the geometries, ab initio (RHF/6-31G) and semiempirical (AM1) theories were used. Oscillator and rotational strengths of all excited states down to 200 nm were compared to experimental absorption and circular dichroism (CD) data. It was found that the sign of the 1Lb Cotton effects obtained for the enantiomers of methaqualone and derivatives of 3-aryl-2-alkylthio-4(3H)-quinazolinones can be correlated unambiguously with the absolute configuration. Furthermore, the sign of the Cotton effect of the π-π* transition of the thiocarbonyl chromophore of 3-aryl-2-mercapto-4(3H)-quinazolinones is suitable for a successful stereochemical correlation. Chirality 10:253-261, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
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    Sympathomimetic enantiomers and asthma (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 262-272 
    Details
    ISSN: 0899-0042
    Keywords: airway ; beta2-agonist ; racemic ; eutomer ; distomer ; hyperreactivity ; bronchospasm ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Airways of asthma patients can become hyperresponsive to airway spasmogens following regular use of isoprenaline or β2-selective sympathomimetics. Hyperreactivity that results from acute exposure of animals to these drugs is pre-empted by vagal section (a procedure which does not influence spasmolytic efficacy of sympathomimetics), is not diminished by antagonism of β2-adrenoceptors and is not associated with loss of responsivity of β2-adrenoceptors in the airways. Since activation, modulation, or blockade of β2-adrenoceptors does not determine this form of hyperreactivity, the possibility that distomers may induce hyperreactivity must be considered. Ocular and vascular responses to distomers of sympathomimetics have long been recognised and, more recently, comparable observations have been made for the airways. Thus, reactivity of guinea-pig airways to spasmogens was increased following exposure to S-isoprenaline, S-salbutamol, or S-terbutaline and exposure to S-isoprenaline or S-salbutamol can intensify symptoms in asthmatics. Regular exposure to the racemate, especially during or following an allergic reaction, predisposes to expression of hyperreactivity, which is nullified, acutely, by the eutomer. These observations imply that biological effects of sympathomimetic distomers may contribute to morbidity and mortality in asthma patients. Chirality 10:262-272, 1998. © 1998 Wiley-Liss, Inc.
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    Immobilized vancomycin as chiral stationary phase in packed capillary liquid chromatography (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 273-280 
    Details
    ISSN: 0899-0042
    Keywords: direct chiral separation ; mobile phase composition ; NSAIDs ; retention model ; vancomycin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fused silica-packed capillary columns containing vancomycin immobilized by reductive amination on an aldehyde-silica were used to separate enantiomers of some non-steroidal anti-inflammatory drugs. Attempts have been made to qualitatively explain the influence of various mobile phase compositions on the enantioselective retention. The effects of mobile phase pH, buffer, and organic modifier concentrations were investigated as well as the influence of salts of hydrophobic ions added to the mobile phase to induce ion pair retention. Chirality 10:273-280, 1998. © 1998 Wiley-Liss, Inc.
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    Carbamates of cellulose bonded on silica gel: Chiral discrimination ability as HPLC chiral stationary phases (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 283-288 
    Details
    ISSN: 0899-0042
    Keywords: chiral HPLC ; cellulose carbamates ; enantiomeric resolution ; warfarin ; flurbiprofen ; lorazepam ; oxazepam ; pindolol ; tertatolol ; nicardipine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four cellulose mixed 10-undecenoate/carbamate derivatives, simultaneously bearing 10-undecenoyl and variously substituted phenylaminocarbonyl groups, were chemically bonded on allylsilica gel. The study of the effect of these substitutions on the performance of the resulting chiral supports, and a comparison with the recently described 10-undecenoate/3,5-dimethylphenylcarbamate derivative, are presented. In this study heptane/2-propanol or heptane/chloroform mixtures were used as mobile phases. Chirality 10:283-288, 1998. © 1998 Wiley-Liss, Inc.
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    Correlation between time reversal symmetry and chirality in certain molecular processes (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 289-293 
    Details
    ISSN: 0899-0042
    Keywords: chirality ; time reversal symmetry ; asymmetric synthesis ; enantiomerism ; isomerism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: If a molecule is identified not only by its static spatial constructions, but also by the motions at the sub-molecular level, application of time reversal symmetry operation to a certain molecule could lead to another distinguishable from the original in the sense of sub-molecular motions, a phenomenon now defined as time reversal isomerism. Assessment of the consideration of certain enantiomers as distinguishable time reversal isomers is suggested in order to evoke a comprehensive interpretation of a likely correlation between the two types of isomerisms. The conceptual basis of a connection between absolute asymmetric synthesis under the influence of external fields and the intrinsic time reversal symmetry violation at the molecular level is also established to encourage new experimental investigations on this theme. Chirality 10:289-293, 1998. © 1998 Wiley-Liss, Inc.
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    Synthesis of regioselectively substituted cellulose derivatives and applications in chiral chromatography (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 294-306 
    Details
    ISSN: 0899-0042
    Keywords: cellulose ; regioselective derivatization ; chiral stationary phases ; liquid chromatography ; enantioseparation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various cellulose-2,3-bis-arylcarbamate-6-O-arylesters and cellulose-2,3-bis-arylester-6-O-arylcarbamates, designed to test the possible combined effects of the known tris-arylcarbamate and tris-arylester classes, were synthesized with high regioselectivity at O-C(6), and their use as CSPs in liquid chromatography for enantiomeric separations was investigated. The separations obtained with the synthesized CSPs were compared to the separations achieved on a self-packed reference column, consisting of cellulose-tris-(3,5-dimethylphenyl-carbamate) as CSP standard. Among the synthesized, regioselectively substituted cellulose derivatives, 2,3-bis-O-(3,5-dimethylphenylcarbamate)-6-O-benzoate-cellulose and 2,3-bis-O-(benzoate)-6-O-(3,5-dichlorophenylcarbamate)-cellulose gave the best CSPs for the separation of the test racemates. CSPs from regioselectively substituted cellulose derivatives seem to exhibit higher selectivities than cellulose-tris-(3,5-dimethylphenylcarbamate) for certain classes of racemic compounds. Chirality 10:294-306, 1998. © 1998 Wiley-Liss, Inc.
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    Enantiomeric separation of rac-indoprofen by a biocatalytic procedure (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 321-324 
    Details
    ISSN: 0899-0042
    Keywords: NSAID ; esterification ; resolution ; Candida antarctica lipase ; rac-Indoprofen ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lipase from Candida antarctica, commercially available immobilised on acrylic resin as Novozym® 435, allows for enantioselective esterification of rac-indoprofen (±)-1, with methanol in a dioxane-toluene solvent system. A double esterification process affords methyl ester (-)-(R)-2 in 85% e.e. and enantiopure (+)-(S)-1, both in good chemical yield. Chirality 10:321-324, 1998. © 1998 Wiley-Liss, Inc.
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    Kinetics of racemization of (+)- and (-)-diethylpropion: Studies in aqueous solution, with and without the addition of cyclodextrins, in organic solvents and in human plasma (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 307-315 
    Details
    ISSN: 0899-0042
    Keywords: configurational stability ; pH ; temperature ; ionic strength ; phosphate buffer concentration ; plasma protein affinity ; native cyclodextrins ; cyclodextrin derivatives ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The configurational stability of (+)- and (-)-diethylpropion [(+)- and (-)-2-(diethyl)-1-phenyl-1-propanone or (+)- and (-)-DEP] was investigated systematically from chemical, pharmaceutical, and pharmacological aspects. The enantiomeric ratio was monitored directly with a recently developed stability-indicating enantioselective HPLC method.In aqueous solutions, the rate of racemization increased non-linearly with increasing pH and with increasing phosphate buffer concentration. The racemization rate showed a positive slope with increasing temperature and decreasing ionic strength.The racemization rates of (+)- and (-)-DEP in the presence of cyclodextrins (CDs) did not differ significantly. CDs that were added to (+)- and (-)-DEP in a molar ratio 5:1 showed the following effects after dissolution in 10 mM phosphate buffer (final pH 6.7): sulfobutyl ether-β-CD (SBE-β-CD) and methylated-β-CD (Me-β-CD) retarded racemization; whereas hydroxypropyl-β-CD (HP-β-CD), acetyl-γ-CD (Ac-γ-CD), acetyl-β-CD (Ac-β-CD), γ-CD, and β-CD showed a weak destabilising effect. In contrast to the described CDs, α-CD distinctly accelerated the rate of racemization.The configurational stability of (+)- and (-)-DEP was also studied under physiological conditions. The half-life of racemization in heparinised human plasma was for both enantiomers determined to be approximately 23-25 min.In phosphate buffer (10 mM, pH 7.4), rac-DEP showed a high, but unselective affinity towards human α1-acid glycoprotein (orosomucoid) immobilised on silica (Chiral AGP).The rate of racemization of the free base of (-)-DEP dissolved in organic solutions generally increases with the polarity of the solvating agent. Chirality 10:307-315, 1998. © 1998 Wiley-Liss, Inc.
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    Determination of the rotational barriers of atropisomeric polychlorinated biphenyls (PCBs) by a novel stopped-flow multidimensional gas chromatographic technique (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 316-320 
    Details
    ISSN: 0899-0042
    Keywords: atropisomeric polychlorinated biphenyls (PCBs) ; Chirasil-Dex ; rotational barrier ; stopped-flow multidimensional gas chromatographic technique ; on-line enantiomerization kinetics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers ΔG
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    Discrimination in resolving systems. III: Pseudoephedrine-mandelic acid (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 325-337 
    Details
    ISSN: 0899-0042
    Keywords: diastereomeric salts ; molecular recognition ; hydrogen bonding ; thermal analysis ; crystallography ; solubility ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (+)-(1S;2S)-Pseudoephedrine and racemic mandelic acid form three distinct diastereomeric salts from solutions in 95% ethanol. The least-soluble phase, a hemihydrate, contains the (2R)-mandelate. A salt phase of intermediate solubility is the unsolvated double salt, containing both the (2R)- and the (2S)-mandelate. The most-soluble salt phase contains the (2S)-mandelate. Mandelate configuration and order of solubility (based on the heats of fusion) is inverted from that found in the same system synthesized from chiral base and acid, and then crystallized from benzene solution. The (2R)-mandelate hemihydrate (-H2O at 349.5K, mp 391K), monoclinic, P21, a = 6.788(5), b = 29.415(35), c = 9.488(10)Å, β = 108.91(8)°, Z = 4 (2 ion-pairs/asymmetric unit). Intermediate double salt (2S)- and (2R)-mandelate, mp 377.6K, anorthic, P1, a = 7.758(4), b = 9.966(5), c = 13.366(6)Å, α = 72.99(4), β = 79.98(4), γ = 70.51(4)°, Z = 1 (2 ion-pairs/asymmetric unit). The (2S)-mandelate (mp 386.2K), orthorhombic, P212121, a = 7.079(6), b = 13.443(10), c = 18.820(14)Å, Z = 4 is identical to a salt made from a combination of enantiomeric moieties from benzene solution. While differing from ephedrine mandelates in configuration at one center, solubilities of pseudoephedrine mandelates in 95% ethanol are much larger. A comparison of molecular structure (non-polar and H-bonding) regions of pseudoephedrine and ephedrine mandelates shows similarities and differences that are tentatively linked to crystal properties. This study reemphasizes the necessity for consistency in solvent use in resolution and in phase identification and comparison because the phases produced are frequently dependent upon the solvent. Chirality 10:325-337, 1998. © 1998 Wiley-Liss, Inc.
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    Manipulation of chiral resolution for isoxazoline-based IIb/IIIa receptor antagonists using various mobile phase additives in subcritical fluid chromatography (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 338-342 
    Details
    ISSN: 0899-0042
    Keywords: additive ; selectivity ; efficiency ; modifier ; subcritical fluid chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Subcritical fluid chromatography (SubFC) using a carbon dioxide-methanol mobile phase is used for the chiral resolution of IIb/IIIa receptor antagonist enantiomers. The chiral resolution of three analogs, each containing two chiral centers, is optimized using various mobile phase additives. The effects that acidic, basic, and neutral additives have on retention, efficiency, and resolution are examined. The additive that gives the best resolution was found to be dependent upon the functionality and charge of the chiral analyte. For charged analytes, additives that act as competing ions of the same charge as the chiral analyte dramatically improve efficiency and resolution. Resolution of neutral chiral analyte enantiomers is also greatly affected by the choice of mobile phase additive. Chirality 10:338-342, 1998. © 1998 Wiley-Liss, Inc.
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    Mechanism of chiral asymmetry generation by chiral autocatalysis in the preparation of chiral octahedral cobalt complex (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 343-348 
    Details
    ISSN: 0899-0042
    Keywords: chiral asymmetry generation ; chiral autocatalysis ; primary nucleation ; secondary nucleation ; chiral cobalt complex ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiral asymmetry generation, the predominant production of one enantiomer in a non-chiral environment, could occur in the production of the chiral complex cis-[CoBr(NH3)(en)2]Br2 by the reaction of [Co(H2O)2{(OH)2Co(en)2}2](SO4)2 with ammonium bromide in an aqueous medium. The main kinetic steps in the reaction system have been determined. During the reaction, the product crystallizes at an early stage. When a very small amount of crystalline enantiomer was added to the reaction system at an early stage, the same enantiomer was produced preferentially; in addition, the enantiomeric excess of the product increased with increasing the stirring rate. Thus, it seems that each enantiomer generates chiral crystals that could self-replicate through secondary nucleation when the solution is stirred; these crystals in turn enhance the production of the same enantiomer. With a computer code that simulates such a kinetic mechanism, it is shown that enantiomeric excess observed in the experiments could be reproduced. Chirality 10:343-348, 1998. © 1998 Wiley-Liss, Inc.
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    Stereoselective renal secretion of carbenicillin in rabbits: Role of the organic anion transporter at the renal brush border membrane (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 349-357 
    Details
    ISSN: 0899-0042
    Keywords: carbenicillin ; stereoselective ; secretion ; transport ; rabbit ; membrane vesicles ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselectivity in the renal secretion of carbenicillin (CBPC) was studied in rabbits. Significant renal secretion of CBPC was observed in vivo, with the secretion of the S-epimer being greater than that of the R-epimer. Stereoselective transport of CBPC was further studied in vitro using basolateral and brush border membrane vesicles prepared from rabbit kidneys. The transport of CBPC by the organic anion transporter into the basolateral membrane vesicles (BLMV) was not stereoselective. In contrast, a distinct stereoselectivity was observed in the transport of CBPC by the organic anion transporter into the brush border membrane vesicles (BBMV), with the transport of the S-epimer being more favorable. Significant epimer-epimer interactions were also observed in the transport into BBMV. The stereoselectivity of the transport of CBPC was calculated from the kinetic parameters with consideration of epimer-epimer interactions and was similar to that observed in vivo. It was concluded that the observed stereoselectivity in the renal secretion of CBPC in vivo reflected that of transport via the organic anion transporter located at the brush border membrane. Chirality 10:349-357, 1998. © 1998 Wiley-Liss, Inc.
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    Emanuel Gil-Av honorary issue of Chirality (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 371-372 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
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    Determination of the enantiomeric purity of commercial Jacobsen's catalyst samples (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 362-363 
    Details
    ISSN: 0899-0042
    Keywords: Jacobsen's catalyst ; enantiomeric purity determination ; chiral HPLC ; cyclodextrin chiral stationary phases ; enantioseparation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A HPLC method is described for the chiral analysis of the commercially available Jacobsen's catalyst. A hydroxypropyl β-cyclodextrin stationary phase was used in conjunction with a nonaqueous, polar-organic mobile phase. The method can be applied to control the enantiomeric purity of the catalyst, which is of great importance for quality control of that product. High accuracy in the determination of trace levels of the unwanted enantiomer in the presence of large amounts of the desired enantiomer is demonstrated. Chirality 10:362-363, 1998. © 1998 Wiley-Liss, Inc.
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    Enantiomeric separation of several cyclic imides on a macrocyclic antibiotic (vancomycin) chiral stationary phase under normal and reversed phase conditions (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 358-361 
    Details
    ISSN: 0899-0042
    Keywords: cyclic imides ; barbiturates ; piperidine-2,6-diones ; mephenytoin ; chiral recognition ; enantioselectivity ; vancomycin chiral stationary phase ; normal-phase mode ; reversed-phase mode ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several cyclic imidic compounds (barbiturates, piperidine-2,6-diones, and mephenytoin) are enantiomerically resolved via high-performance liquid chromatography (HPLC) on a macrocyclic antibiotic covalently bonded to a silica gel support. The Chirobiotic V chiral stationary phase (CSP) column contains the antibiotic vancomycin as the chiral selector. The results of the analysis show that the substituents at the chiral carbon position of the racemic drugs affect chiral resolution. In addition, ring size may also play a role when considering the formation of analyte-CSP inclusion complexes. Contrary to the piperidine-2,6-diones, the chromatographic parameters for the barbiturates are much the same under normal- or reversed-phase conditions. The details of these results are discussed. Chirality 10:358-361, 1998. © 1998 Wiley-Liss, Inc.
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    Emanuel Gil-Av (1916-1996): A man with a legacy (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 373-374 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
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  • 78
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    Separation of nicotine and nornicotine enantiomers via normal phase HPLC on derivatized cellulose chiral stationary phases (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 364-369 
    Details
    ISSN: 0899-0042
    Keywords: (±)nicotine ; (±)nornicotine ; chiral separation ; enantiomers ; normal phase HPLC ; mobile phase additive ; cellulose-based chiral stationary phase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes the enantiorecognition of (±)nicotine and (±)nornicotine by high-performance liquid chromatography using two derivatized cellulose chiral stationary phases (CSPs) operated in the normal phase mode. It was found that different substituents linked to the cellulose backbone significantly influence the chiral selectivity of the derivatized CSP. The results showed that, in general, the tris(4-methylbenzoyl) cellulose CSP (Chiralcel OJ) surpasses tris(3,5-dimethylphenyl carbamoyl) cellulose CSP (Chiralcel OD). On the former column, the resolution (±)nicotine and (±)nornicotine enantiomers depended largely on mobile phase compositions. For the separation of the nicotine enantiomers, the addition of trifluoroacetic acid to a 95:5 hexane/alcohol mobile phase greatly improved the enantioresolution, probably due to enhanced hydrogen bonding interactions between the protonated analytes and the CSP. For (±)nornicotine separation, a reduction in the concentration of alcohol in the mobile phase was more effective than the addition of trifluoroacetic acid. Possible solute-mobile phase-stationary phase interactions are discussed to explain how different additives in the mobile phase and different substituents on the cellulose glucose units of the CSPs affect the separation of both pairs of enantiomers. Chirality 10:364-369, 1998. Published 1998 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
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    Chiral separation of enantiomers via selector/selectand hydrogen bondings (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 382-395 
    Details
    ISSN: 0899-0042
    Keywords: selector/selectand associates ; hydrogen bonding ; chiral separation ; chiral phases ; enantioselectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The progress made in the development of chiral stationary phases based on hydrogen-bonding selector/selectand associates is reviewed here. The structure of the different selectand/selector systems was established through X-ray diffraction and other spectroscopic techniques. The structure of the energetically more stable diastereomeric-associate was then correlated to the chromatographic results, namely to the elution order and the enantioselectivity of each of the systems. Chirality 10:382-395, 1998. © 1998 Wiley-Liss, Inc.
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    A closer study of chiral retention mechanisms (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 375-381 
    Details
    ISSN: 0899-0042
    Keywords: retention mechanisms ; separation of enantiomers ; chiral stationary phases ; equilibrium isotherms ; bonding ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The retention mechanisms and the separation of enantiomers on the classes of chiral stationary phases which are made by bonding isolated groups on the surface of an adsorbent are discussed. It is shown that retention on these phases originates from mixed mechanisms and how the individual contributions of these two mechanisms can be separated, by determining and modeling the equilibrium isotherms. A contribution originating from interactions of the isomers with the nonselective sites (type-I) and another one due to interactions with the enantioselective sites (type-II) can be determined and their importance studied as a function of several parameters, e.g., temperature or pH. This approach is illustrated with results obtained with different pairs of enantiomers on bovine serum albumin, 4-methylcellulose tribenzoate, or cellobiohydrolase immobilized on silica. Chirality 10:375-381, 1998. © 1998 Wiley-Liss, Inc.
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    Tripodal trispeptide selector as a model for establishing the importance of hydrogen-bonding in enantiomer-separation (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 396-404 
    Details
    ISSN: 0899-0042
    Keywords: chirality ; helicity ; GC-stationary phase ; conformations ; 1H-NMR-studies ; molecular mechanics calculations ; enantiomer separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The manner of hydrogen-bonding to peptide selectors in enantiomer separation is examined with the help of a structural model. This model relies on a C3-symmetric trispeptide selector, which is stabilized by a network of distinct intramolecular hydrogen bonds. A combination of experimental and theoretical tools enables us to identify the lowest-energy conformation of the trispeptide selector and the sites of selector-substrate interactions. Experimental tools include temperature dependent 1H-NMR studies, 1D-NOE-measurements, and titration experiments, with the theoretical tools being EFF and CFF91 molecular mechanics calculations. The structural information deduced from these investigations is shown to bear on the enantioseparation of the corresponding chiral stationary phase towards derivatized amino acids. These observations, taken together, help to rationalize the mode of enantiomer-separation by amide phases as involving predominantly C7-hydrogen bonding sites. Chirality 10:396-404, 1998. © 1998 Wiley-Liss, Inc.
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    The chiral code: From DNA primary structures to quaternary assemblies (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 405-414 
    Details
    ISSN: 0899-0042
    Keywords: chiral-discrimination ; homochirality ; stereospecificity ; self-assembly ; supercoiling ; cholesteric mesophase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nucleic acids are characterized by a predominant right-handed helical configuration that derives from the chirality of the sugar moiety. Hitherto, only “local” effects of this helical asymmetry, exemplified by DNA interactions with small compounds, have been documented. The results described in this study indicate that an enhanced asymmetry is required for the manifestation of chiral effects in DNA self-assembly processes or for chiral discrimination upon interactions with peptides. Two cases in which the intrinsic DNA asymmetry is enhanced are reported: rod-like superhelical species derived from linear DNA molecules, and topologically constrained supercoiled DNA. In the first case, the superhelical grooves within the DNA rods allow for a stereospecific complexation with peptides, resulting in chiral discrimination. In the second case, it is shown that the properties of cholesteric assemblies derived from supercoiled DNA are strictly determined by the enhanced asymmetry associated with molecular supercoiling. The results allow for new reflections on the concept of molecular complementarity, and indicate that spontaneously obtained chiral DNA mesophases might have played a key role in determining terrestrial homochirality. Chirality 10:405-414, 1998. © 1998 Wiley-Liss, Inc.
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    Aspects of spontaneous separation of enantiomers in two- and three-dimensional crystals (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 415-424 
    Details
    ISSN: 0899-0042
    Keywords: chiral separation ; two- and three-dimensional crystals ; grazing incidence X-ray diffraction ; atomic force microscopy ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spontaneous separation of enantiomers in two- and three-dimensional crystals is driven by the same thermodynamic and kinetic factors. However, amphiphilic crystalline monolayers at an interface cannot possess a center of inversion, the most common symmetry element in bulk crystals. This fact should, in principle, lead to better chances for spontaneous separation in the Langmuir or Langmuir-Blodgett monomolecular films. On the other hand, the monolayers of most amphiphiles studied to date incorporate long aliphatic chains that have an intrinsic tendency to pack in a herring-bone motif requiring glide plane symmetry, thus creating a bias towards racemate formation. Moreover, 2-D crystals supposedly have a much higher degree of molecular and therefore enantiomeric disorder compared to bulk crystals. All these factors necessitate a careful choice of molecules to guarantee enantiomeric separation in two dimensions. Unambiguous detection of spontaneous resolution in 2-D appears to require atomic resolution of molecular packing arrangement, which can in principle be obtained by grazing incidence X-ray diffraction or atomic force microscopy, whereas in bulk solids spontaneous resolution can be easily detected by various macroscopic methods. This short review provides analogies between spontaneous separation in 3-D and recent examples in 2-D, showing that spontaneous separation generally depends upon subtle differences in molecular structure. Chirality 10:415-424, 1998. © 1998 Wiley-Liss, Inc.
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    Determination of the rotational barriers of atropisomeric polychlorinated biphenyls (PCBs) by a novel stopped-flow multidimensional gas chromatographic techniqueThis article was orginally published in Chirality, Volume 10, Number 4, pages 316-320. As it is suited to the theme of this issue, this article appears again here. All citations to this article should use the original volume, issue, and page range. (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 425-429 
    Details
    ISSN: 0899-0042
    Keywords: atropisomeric polychlorinated biphenyls (PCBs) ; Chirasil-Dex ; rotational barrier ; stopped-flow multidimensional gas chromatographic technique ; on-line enantiomerization kinetics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers ΔG† (T) of the four atropisomeric polychlorinated biphenyls (PCBs) 2,2′,3,5′,6-pentachlorobiphenyl (PCB 95), 2,2′3,3′,4,6′-hexachlorobiphenyl (PCB 132), 2,2′,3,3′,6,6′-hexachlorobiphenyl (PCB 136), and 2,2′,3,4′,5′,6-hexachlorobiphenyl (PCB 149) were determined via on-line enantiomerization kinetics by a new stopped-flow multidimensional gas chromatographic technique (stopped-flow MDGC) employing Chirasil-Dex as chiral stationary phase for enantiomer separation. The calculated rotational barriers ΔG† (T) of the trichloro-ortho-substituted atropisomers are 184 ± 2 kJ/mol for PCB 95, 189 ± 4 kJ/mol for PCB 132, and 184 ± 1 kJ/mol for PCB 149 at 300°C. The rotational barrier ΔG† (T) of tetrachloro-ortho-substituted PCB 136 is at least (or higher than) 210 kJ/mol at 320°C. Chirality 10:425-429, 1998. © 1998 Wiley-Liss, Inc.
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    Chiral recognition of phthalides and lactams (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 430-433 
    Details
    ISSN: 0899-0042
    Keywords: Whelk-O 1 ; chromatography ; HPLC ; enantiodifferentiation ; heterocycles ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In concert with a larger study of the processes by which chiral stationary phase CSP 1 differentiates between enantiomers, we have investigated the chromatographic separation of the enantiomers of a series of aryl-substituted heterocycles of systematically varied structure. A mechanistic picture of how these and similar resolutions occur is emerging. The mechanistic hypothesis described herein is of predictive value. Chirality 10:430-433, 1998. © 1998 Wiley-Liss, Inc.
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    Highly enantioselective HPLC separations using the covalently bonded macrocyclic antibiotic, ristocetin A, chiral stationary phase (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 434-483 
    Details
    ISSN: 0899-0042
    Keywords: ristocetin A ; macrocyclic antibiotic ; enantiomeric separations ; underivatized amino acids ; chiral stationary phase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The macrocyclic glycopeptide, ristocetin A, was covalently bonded to a silica gel support and evaluated as a liquid chromatographic (LC) chiral stationary phase (CSP). Over 230 racemates were resolved in either the reversed-phase mode, the normal-phase mode, or the polar-organic mode. The retention behavior and selectivity of this CSP were examined in each mode. Optimization of separations on this column is discussed. The ristocetin A CSP appeared to be complimentary to other glycopeptide CSPs (i.e., vancomycin and teicoplanin). Column stability was excellent. The CSP was not irreversibly altered when going from one mobile phase mode to another. Chirality 10:434-483, 1998. © 1998 Wiley-Liss, Inc.
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    Determination of the enantiomers of albuterol in human and canine plasma by enantioselective high-performance liquid chromatography on a teicoplanin-based chiral stationary phase (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 484-491 
    Details
    ISSN: 0899-0042
    Keywords: salbutamol ; chiral separation ; validated assay ; fluorescence detection ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sensitive enantioselective high-performance chromatographic (HPLC) method was developed and validated to determine low levels of (-)-R and (+)-S-albuterol in plasma. Baseline resolution was achieved by using a teicoplanin-based chiral stationary phase with a polar organic mobile phase consisting of methanol/acetonitrile/glacial acetic acid/diethylamine, 40:60:0.3:0.2, (v/v/v/v) and a flow-rate of 1.0 ml/min. Enantioselectivity (α) equaled 1.18 and resolution (Rs) equaled 1.8. By using fluorescence detection maximized at 230 and 310 nm for excitation and emission, respectively, concentrations of each enantiomer could be measured down to 125 pg/ml from a 1-ml plasma sample. Initially, the method was applied to plasma samples from a small single-dose inhalation study of racemic albuterol in a human volunteer and, later, to in vivo samples from a canine inhalation study of the single enantiomer, (-)-R-albuterol. Results from the canine study showed that no chiral inversion of (-)-R-albuterol occurs in the dog. Chirality 10:484-491, 1998. © 1998 Wiley-Liss, Inc.
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    Achiral derivatization as a means of improving the chromatographic resolution of racemic alcohols on benzoylcellulose CSPs (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 492-498 
    Details
    ISSN: 0899-0042
    Keywords: racemate ; enantiomer ; HPLC ; chiral stationary phase ; benzoylcellulose ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The advantages that can be gained from derivatization of various racemic aliphatic and aromatic alcohols prior to enantiomeric chromatographic separation have been systematically investigated for a series of benzoate derivatives. Three cellulose-based CSPs available in the pure polymeric form - tribenzoyl cellulose (TBC), meta-methylbenzoyl cellulose (MMBC), and para-methylbenzoyl cellulose (PMBC) - were selected and several benzoate derivatives varying in the nature and the position of the substituent on the benzoyl group were prepared and analysed. TBC clearly gives the broadest application range, and among the different benzoate esters the best selectivity was generally obtained with either the 4-methoxybenzoate or the 4-methylbenzoate derivatives. Based on these results, some empirical rules could be formulated for optimizing the enantiomeric separation of racemic alcohols, which make up one of the most important classes of chemical substances used as drugs and biocides, or as building blocks for their synthesis. An application of this approach to the preparative separation of the enantiomers of a drug intermediate is also shown. Chirality 10:492-498, 1998. © 1998 Wiley-Liss, Inc.
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    Enantioselective capillary gas chromatography in the investigation of stereochemical correlations of terpenoids (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 499-504 
    Details
    ISSN: 0899-0042
    Keywords: enantioselective capillary gas chromatography ; cyclodextrin derivatives ; stereochemistry of terpenes ; monoterpenes ; essential oils ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary gas chromatography employing the unique selectivities of specifically substituted cyclodextrins is highly suited for stereochemical investigations of terpenoid compounds. The analysis of many essential oils have shown that monoterpene derivatives regularly occur as enantiomeric mixtures. In the case of sesquiterpene hydrocarbons, liverworts (Hepaticae) and other lower organisms usually biosynthesize compounds of opposite stereochemistry as compared to higher plants and enantiomeric mixtures occur only occasionally. The investigation of diterpene hydrocarbons has so far shown no indication of the presence of both enantiomers in the same plant. Chirality 10:499-504, 1998. © 1998 Wiley-Liss, Inc.
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    Determination of drug levels in human serum by circular dichroism (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 507-512 
    Details
    ISSN: 0899-0042
    Keywords: chiroptical method ; drug analysis ; β-lactam antibiotics ; CD spectroscopy ; human fluids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study of the applicability of circular dichroism (CD) for the determination of drug levels in human serum is described and a new method for the quantitative determination of optically active absorbing drugs having Cotton effects at wavelengths above 250 nm in human serum and/or plasma is proposed. The principal advantages of this method are speed, economy, and simplicity, no derivatization or chromatographic separation steps being needed. The validity of the CD determination was confirmed by analysis of variance, β-lactam antibiotics being chosen as model drugs. In addition, the validation studies performed confirm the accuracy and precision of the proposed method. For β-lactam antibiotics lacking Cotton effects above 250 nm, an alternative method based on the extraction of the drug from serum is considered. Chirality 10:507-512, 1998. © 1998 Wiley-Liss, Inc.
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    Unexpected difference in enantioselective retention on cellulase (CBH I) silica stationary phase caused by exchange of potassium for sodium ion in the mobile phase (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 513-518 
    Details
    ISSN: 0899-0042
    Keywords: CBH I ; cellulase ; cation ; sodium ; potassium ; enantioselectivity and temperature ; ionic strength ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An increase in both retention and enantioselectivity for some β-blocking agents was observed when exchanging potassium to sodium ion in the buffer used as mobile phase. A large effect of ionic strength on retention was observed, while the enantioselectivity was constant. Chirality 10:513-518, 1998. © 1998 Wiley-Liss, Inc.
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    Weak interactions and the tunneling racemization (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 519-521 
    Details
    ISSN: 0899-0042
    Keywords: optical activity of enantiomers ; weak interactions ; stability of optical activity ; racemization ; tunneling effect ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Assuming the active molecule as a two-level system, we calculate the racemization, due to the tunneling effect, taking into account the effects of the weak interactions and of an external potential. We show that the weak interactions would block the tunneling racemization of enantiomers in compressed gases and liquids. Chirality 10:519-521, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 1 Tab.
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  • 93
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    Electronic Resource
    Structure and substituent effect on chiral separation of some 4a-methyl-2,3,4,4a-tetrahydro-1H-fluorene derivatives and 4a-methyl-1,2,3,4,4a,9a-hexahydro-fluoren-9-one derivatives on CTA-I and chiralcel OJ chiral stationary phases (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 522-527 
    Details
    ISSN: 0899-0042
    Keywords: chiral HPLC ; quantitative substituent effect ; recognition mechanism ; fluorene derivative-chiral separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chromatographic parameters for 12 structurally related compounds in the 4a-methyl-2,3,4,4a-tetrahydro-1H-fluorene and 4a-methyl-1,2,3,4,4a,9a-hexahydro-fluoren-9-one series are reported on CTA-I and Chiralcel OJ chiral stationary phases. Arrangement of the k' values according to configurationally related enantiomer series (Class I and Class II) and not according to the actual order of elution, allows the treatment of the data by linear correlation with structure and substituent effect. A detailed analysis of the capacity factor variation with respect to the structural changes shows clearly that the framework and substitution effects do not result in the same response on the two cellulose ester chiral stationary phases. More interestingly, it emerges that chiral discimination may be attributed to certain areas of the molecule, these areas being different in the interaction within CTA-I and Chiralcel OJ. Furthermore, our analysis points out the relevance of attempting to develop quantitative relationships for configurationally related series of enantiomers (in our case Class I and Class II), the main effort being devoted to the understanding of the capacity factor variation in each class rather than of the α values, which are derived entities. Chirality 10:522-527, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 94
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    Electronic Resource
    Drugs for chiral discrimination: Non-coded amino acids and dipeptides by asymmetric hydrogenation (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 535-539 
    Details
    ISSN: 0899-0042
    Keywords: asymmetric hydrogenation ; non-coded amino acids ; enantioselectivity ; dipeptides ; diastereoselectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomers of Propranolol, Pindolol, and Carazolol, well-known β-blockers, have been used to prepare cationic aminophosphine phosphinite rhodium complexes. Propraphos-Rh and Pindophos-Rh are very efficient catalysts in the asymmetric hydrogenation of N-Boc-protected unusual dehydroamino acid derivatives. Carazolol-Rh is less suitable in both activity and enantioselectivity. Under the same conditions, N-Boc-protected dehydrodipeptides are hydrogenated with diastereoselectivities between 70 and 90% de. Chirality 10:535-539, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
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  • 95
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    Electronic Resource
    Extent of chiral inversion of the 2-arylpropionic acids by Cordyceps militaris (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 528-534 
    Details
    ISSN: 0899-0042
    Keywords: chiral inversion ; ibuprofen ; ketoprofen ; flurbiprofen ; indoprofen ; suprofen ; fenoprofen ; metabolism of 2-arylpropionic acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fungus Cordyceps militaris has been previously shown to be capable of inverting the chirality of 2-phenylpropionic acid from its (R)-enantiomer to its (S)-antipode. The structure of this compound is similar to the 2-arylpropionic acid non-steroidal anti-inflammatory drugs, which have also been reported to undergo a similar chiral inversion process in mammals and man. We report here an investigation into the substrate specificity of the enzyme system present in C. militaris using pure enantiomers and racemates of ibuprofen and ketoprofen and racemates of indoprofen, suprofen, flurbiprofen, and fenoprofen and the structurally related compounds 2-phenylbutyric acid and 2-phenoxypropionic acid as substrates, using optimised incubation conditions developed for the inversion of 2-phenylpropionic acid. The results demonstrated that C. militaris is capable of inverting the chirality of all the compounds investigated, which suggests that the active sites of the enzymes are very flexible with regard to the molecular dimensions of the substrate molecule and the spatial occupation of the groups surrounding the chiral centre. Metabolism of all the substrates was observed but the rate of metabolism varied extensively depending on the substrate. Achiral HPLC analysis was used to detect any potential metabolites and the results suggested that the site of the metabolism appeared to be at the aliphatic side groups only, with the aromatic ring being left intact in all cases. These results suggest that C. militaris could be a valuable tool in the investigation of the prospective metabolic fates of new 2-arylpropionic acids during their development. Chirality 10:528-534, 1998. © 1998 Wiley-Liss, Inc.
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  • 96
    Electronic Resource
    Electronic Resource
    Gas chromatographic separation of PCB atropisomers on cyclodextrin stationary phases (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 540-547 
    Details
    ISSN: 0899-0042
    Keywords: chiral capillary columns ; PCB enantiomers ; temperature dependence of enantioselectivity ; effect of polysiloxane polarity on enantioselectivity ; enantiomeric ratio ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas chromatographic study on chiral separation of PCBs was performed in a series of capillary columns coated with 0.1-μm film of modified cyclodextrin (CD) stationary phases. The preparation of columns included the investigation into the effect of the content of cyclodextrin derivative in polysiloxane, the type of polysiloxane and temperature of analysis on the quality of separation and retention of atropisomers of 15 selected PCB congeners. The separation properties towards PCBs of stationary phase heptakis(2,3-di-O-methyl-6-O-tert-butyl-dimethylsilyl)-β-CD dissolved in SE-30, SE-54, and OV-1701, were compared with those of 6-monokis-octamethylene-permethyl-β-CD anchored to polydimethylsiloxane polymer (ChirasilDex column, Chrompack, Middelburg, The Netherlands) and octakis(2,6-di-O-methyl-3-O-pentyl)-γ-CD in OV-1701 (MEGA, Legnano (MI), Italy). The correctness of quantitative enantiomer ratio determination was assesed by splitless analysis of PCBs reference solutions in concentration of 1.25-125 ng/ml (PCBs 45 and 91) and 2.5-250 ng/ml (PCB 95) (the PCB congeners are numbered according to IUPAC). Chirality 10:540-547, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 97
    Electronic Resource
    Electronic Resource
    Eighth International Symposium on Chiral Discrimination (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 555-555 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Type of Medium: Electronic Resource
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  • 98
    Electronic Resource
    Electronic Resource
    Separation of enantiomers of drugs by capillary electrophoresis, part 7: Gamma-cyclodextrin as chiral solvating agent (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 548-554 
    Details
    ISSN: 0899-0042
    Keywords: capillary electrophoresis ; enantiomer separation ; chiral drugs ; γ-cyclodextrin ; gamma-cylcodextrin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Following an extended chiral drug screening program by capillary zone electrophoresis (CZE), the enantioseparation of 86 racemic drugs was tested with γ-cyclodextrin as a chiral solvating agent. Unified conditions were applied to all experiments. In total, 18 drug racemates were separated, 13 entries thereof that had not been separated at the lower CSA concentration applied in an earlier stage of the project. A comparison of the data with the results obtained for α- and β-cyclodextrin points to the significance of partial penetration (“side-on binding”) of aryl groups into the cyclodextrin cavity. Chirality 10:548-554, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 99
    Electronic Resource
    Electronic Resource
    Enantioselective synthesis of α-aminophosphonic acid derivatives by hydrogenation (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 564-572 
    Details
    ISSN: 0899-0042
    Keywords: asymmetric hydrogenation ; aminophosphine phosphinites ; rhodium complexes ; dehydro aminophosphonic acids ; NMR ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiral α-aminophosphonic acid derivatives are efficiently synthesized by asymmetric hydrogenation of the prochiral N-acyl-α,β-dehydroaminophosphonates. PROPRAPHOS-Rh-catalysts from readily available (S)- and (R)-Propranolol proved to be suitable in the homogenous reaction affording an enantiomeric excess of 87-92% with high rate. The aminophosphonic acid derivatives and precursors were fully characterized by 1H, 13C, and 31P NMR spectroscopy. Chirality 10:564-572, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    Synthesis and optical properties of the chloroquine enantiomers and their complexes with ferriprotoporphyrin IX in aqueous solution (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 556-563 
    Details
    ISSN: 0899-0042
    Keywords: chloroquine ; enantiomers ; synthesis ; pyroglutamic acid ; ferriprotoporphyrin IX ; circular dichroism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chloroquine (CQ) enantiomers were prepared by a novel synthesis starting from either (S)- or (R)-pyroglutamic acid. Light-absorption spectra of CQ and of complexes of ferriprotoporphyrin IX (FP) with CQ were measured in dilute aqueous solutions at pH 7.3 and 11.3. Spectrophotometric titrations at these pH values indicated a mole ratio of FP:CQ of 2:1 for the FP-CQ aggregated complexes. Aqueous solutions of each of the CQ enantiomers (pH 7.3) and of their complexes with FP (pH 11.3) were investigated by circular dichroism (CD). At pH 11.3, the complexes of the two enantiomers showed CD-band extrema of opposite sign at 409-410 nm. CD-titrations at pH 11.3 confirmed a predominant mole ratio of FP:CQ of 2:1 in the complex. The possible origin of the optical activity of the FP-CQ complexes is discussed. Chirality 10:556-563, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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