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  • 1985-1989  (6,224)
  • 1975-1979  (3,817)
  • Analytical Chemistry and Spectroscopy  (9,090)
  • Ultrastructure  (951)
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Year
  • 1
    ISSN: 1432-0428
    Keywords: Islet amyloid polypeptide ; Pancreatic islets ; B cells ; Ultrastructure ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Islet amyloid polypeptide is a novel 37 amino-acid-residues polypeptide which has been isolated from amyloid deposits in an insulinoma, and in human and cat islets of Langerhans. The molecule has 46% homology with the calcitonin gene-related peptide. Light microscopy examination of the pancreas shows that islet amyloid polypeptide immunoreactivity is restricted to the islet B cells. The present study utilized a rabbit antiserum against a synthetic peptide corresponding to positions 20–29 of islet amyloid polypeptide, a sequence without any amino-acid identity with calcitonin gene-related peptide. By applying the immunogold technique at the ultrastructural level, it was shown that both insulin and islet amyloid polypeptide immunoreactivity occurs in the central granular core of the human B cell secretory granules, while the A cells remain unlabelled. The demonstration that islet amyloid polypeptide is a granular protein of the B cells may indicate that it is released together with insulin. Further studies are necessary to evaluate the functional role of islet amyloid polypeptide.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 198 (1989), S. 92-102 
    ISSN: 1432-041X
    Keywords: Vitellogenesis ; Xenopus oocyte ; Yolk-platelet membrane ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The yolk platelets ofXenopus laevis have been studied by thin-section and freeze-fracture electron microscopy to characterize the boundary membrane during yolk formation. Throughout vitellogenesis, large yolk platelets are in close contact with smaller nascent yolk organelles. Two types of primordial yolk platelets (I and II) have been discriminated. After membrane fusion these precursors can be completely incorporated into the main body of existing platelets, numerous yolk crystals then merge and form one uniformly stratified core. Lipid droplets are tightly attached to the membrane at all developmental stages of yolk platelets. A direct connection of endoplasmic reticulum to the membranes of yolk platelets was not observed. On freezeetching replicas, yolk-platelet membranes present fracture faces with intramembranous particles (IMP) of various sizes and a heterogeneous distribution of approximately 200–600 IMP/μm2 at the E face, and 1200–2100 IMP/μm2 at the P face. Again, this presentation of the membrane exhibits neither anastomoses to the endoplasmic reticulum, nor caveolae that exclude the uptake of yolk-containing vesicles into these yolk organelles. Proteinaceous yolk platelets tend to fracture along their periphery through the superficial layers.
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  • 3
    ISSN: 1432-0568
    Keywords: Monkey ; Ultrastructure ; Pinealocytes ; Axon terminals ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present study described the normal ultrastructure of the monkey pineal gland. The gland was composed of the principal pinealocytes, intramural neurons and glial cells. The nucleus of the pinealocytes was deeply infolded with evenly distributed chromatin materials. The abundant cytoplasm was rich in organelles including the well-developed Golgi apparatuses, multivesicular bodies, dense-cored vesicles and widely scattered free and polyribosomes. A variety of axon terminals was observed and the majority of them contained pleomorphic agranular vesicles with a few large dense-cored vesicles. A few terminals showed flattened vesicles or small dense cored vesicles. Some of the axon terminals formed synaptic contacts with the cell bodies of pinealocytes. These synapses were mainly concentrated in the posterior third of the gland. The occasional intramural neurons observed were postsynaptic to axon terminals containing round agranular vesicles. The sources of the nerve fibres and terminals forming synaptic junctions with pinealocytes and intramural neurons were discussed.
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  • 4
    ISSN: 1432-0568
    Keywords: Sympathetic ganglion ; Binucleate cells ; Ultrastructure ; Feulgen staining ; Computerized image analysis ; DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relative proportion, ultrastructure and DNA-content of the binucleate cells in the celiac superior mesenteric ganglion of the guinea pig was studied using light and electron microscopy as well as computerized image analysis of Feulgen stained cells. The number of mono — versus binucleate cells was found to vary with stage of development with about 40% of the cells being binucleate in adult animals and 50% in late prenatal stage. No difference in ultrastructure was observed between the nuclei of the two cell types. The binucleate cells contain twice the amount of DNA found in the mononucleate cells.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 180 (1989), S. 175-178 
    ISSN: 1432-0568
    Keywords: Paratympanic organ ; Reciprocal synapses ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The innervation pattern of the paratympanic organ was studied by TEM. The paratympanic organ is a small tapering vesicle, typical of birds, situated in the medial wall of the tympanic cavity; it contains hair cells which are similar to type II receptors of the acoustic-lateral system; these cells are characterised by synapses which are not only afferent and efferent, as previously described, but also reciprocal with efferent fibers. Our observation revealed some efferent nerve fibers which form a relationship with hair cells containing synaptic bodies situated next to the plasma membrane and near the fibers themselves. Since synaptic bodies are commonly considered to be the site where the transmission of the impulse from the receptor to the nerve fiber takes place, our pictures suggest that the efferent fibers and hair cells may be either presynaptic or postsynaptic with respect to each other in the paratympanic organ. The hypothesis is formulated that reciprocal synapses allow interaction between hair cells, thus determining an increase in the contrast of information sent by the paratympanic organ to the CNS.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 179 (1989), S. 591-604 
    ISSN: 1432-0568
    Keywords: Fetus ; Membranes ; Placenta ; Green monkey ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study examined developmental changes in fetal membranes and placenta of Cercopithecus aethiops from a Carnegie developmental stage 12 embryo to nearterm fetuses. Ultrastructurally, yolk sac cells (endoderm and mesothelium) were similar to comparable stages in other primates. Endodermal cells had few apical microvilli, abundant rough-endoplasmic reticulum, electron dense mitochondria and dense bodies. In contrast, mesothelial cells were squamous with numerous microvilli, small mitochondria and a few short strands of rough endoplasmic reticulum. Amnion cells early in gestation were squamous with few microvilli, large glycogen deposits and poorly developed cytoplasmic components. Tight junctions and desmosomes held adjacent cells together. The basal surface was smooth and the basal lamina was distinct. As development proceeded the amniotic cells became cuboidal and possessed numerous microvilli. Cytoplasmic organelles were better developed and glycogen deposits increased by mid-gestation. A thick layer of microfibrils and collagen fibers was prominent below the basal lamina. Near-term, the glycogen had virtually disappeared and the amount of lipid droplets increased. Basal infoldings and podocytic processes and the extracellular matrix had increased. The smooth chorion consisted of pseudostratified columnar cells. Cells had short microvilli, numerous granules and vesicles of variable size and electron density in early gestation. With increasing age, amounts of granules and vesicles decreased, as the endoplasmic reticulum became prominent. The chorionic trophoblast was a continuous layer in mid-pregnancy and its cells had well-developed organelles and inclusions. Late in gestation, the trophoblastic layer became discontinuous and wide intercellular spaces and channels were present. In the placenta, the trophoblastic elements showed features characteristic of primate placenta.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 179 (1989), S. 435-442 
    ISSN: 1432-0568
    Keywords: Ultrastructure ; In vitro fertilization ; Bovine ; Ova ; Cortical granules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Heifers were superovulated by PMSG or FSH, and oestrus was induced by prostaglandin. One group of animals was ovariectomized 19–26 h after the LH peak, the content of preovulatory follicles aspirated, and the oocytes processed for in vitro fertilization. Another group was inseminated and ova were collected from the oviducts for study of in vivo fertilization. All ova were examined ultrastructurally. The developmental rate following in vitro fertilization was delayed compared to fertilization in vivo. A high proportion of the in vitro fertilized ova showed polyspermic penetration of the zona pellucida, and supernumerary spermatozoa were found in the ooplasm of some ova. In vivo fertilization was associated with release and subsequent dispersal of the cortical granule content in the perivitelline space. In contrast to this the released granule content of the in vitro fertilized ova remained undispersed close to the oolemma. This feature may account for the high incidence of polyspermic penetration of the zona pellucida. In addition, the study provided an ultrastructural visualization of the initial contact between the equatorial segment of the spermatozoon and the microvilli of the oocyte, and the subsequent internalization of the sperm head.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 179 (1989), S. 497-501 
    ISSN: 1432-0568
    Keywords: Parotid gland ; Ultrastructure ; Amylase ; Secretion ; Isoproterenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of continuous light on ultrastructural organization and sympathetic secretory responses of the rat parotid gland are reported. After 50 days of continuous light exposure, the fine structure of the parotid gland exhibited features of enhanced secretory activity as judged by the striking development of rough endoplasmic reticulum and Golgi complexes, the depletion of secretory granules and the increased turnover of secretory cells. The secretory responses of parotid gland to isoproterenol revealed that continuous light induced a 30% increase in amylase release. This secretory hyperactivity appears to be related to a postsynaptic supersensitivity of sympathetic fibers of the autonomic nervous system.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 180 (1989), S. 103-108 
    ISSN: 1432-0568
    Keywords: Ultrastructure ; Gut ; Endocrine cells ; Testudo graeca ; Chelonia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The digestive tract of Testudo graeca (Chelonia) was investigated by means of electron microscopy using both conventional and immunocytochemical techniques. EC-, L-, D-, G-, B-, N- and EC-L-cells were detected. These cells share several common ultrastructural characteristics with the endocrine cells of mammals (i.e. clear cytoplasm, prominent Golgi apparatus, secretory granules etc.). EC and D1 cells have so far not been described in the esophagus of any animal species; in the present study these cells have been observed in the esophagus of T. graeca. Of special interest was the presence of B-cells in the intestine, suggesting that the migration of B-cells from the gut to the pancreas to constitute pancreatic islets is not concluded in T. graeca. The present study demonstrates that the gut endocrine system of T. graeca is a complex structure containing a large variety of endocrine cell types similar in morphology to those found in higher vertebrates.
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  • 10
    ISSN: 1432-0568
    Keywords: Cecum ; Germ-free rat ; Microflora inoculation ; Morphometry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The structural changes of the cecal wall in germfree rats were observed at regular intervals after the inoculation of fecal microflora from conventional rats. Quantitative light microscopy showed that most of the elements in the cecal wall increased at 12 or 24 h and reached peak values at 4 days after inoculation. On the 7th day, they decreased approximately to the values for conventional rats. The crypts were bent or widely open till 24 h but were not after the 4th day. Hyperplasia of the crypt epithelial cells including mucous-type cells was observed following microbial inoculation. Electron microscopy revealed that most of the epithelial cells lining the mucosa were typical columnar cells. Desquamation of the epithelial cells and contraction of the muscle fibers were often seen on 4th day. The mucous-type cells were divided into two types, goblet and non-goblet mucous-type cells. Reduction of cecal volume after microbial inoculation may be mainly caused by muscle contraction in the early period and hyperplasia and desquamation of the epithelial cells may suggest their role as the first and non-specific defense line prior to operation of the specific immune system.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 77 (1989), S. 258-266 
    ISSN: 1432-0533
    Keywords: Neurofibrillary tangles ; Alzheimer's disease ; Pick bodies ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have studied the immunohistochemical reactivity and ultrastructure of both neurofibrillary tangles (NFTs) occurring with severe neurofibrillary diseases, and Pick bodies (PBs) associated with Pick's disease. The NFTs and PBs did not react immunohistochemically with the anti-nonphosphorylated neurofilament monoclonal antibody irrespective of whether they were pretreated with alkaline phosphatase. In granular neurons of the dentate fascia of Ammon's horn in cases of dementia of the Alzheimer type (DAT), NFTs either resembled PB-like inclusion bodies (Horoupian's inclusion bodies) in form, or had a perinuclear structure. Immunohistochemically and ultrastructurally, the NFTs in the dentate fascia in cases of DAT, including Horoupian's inclusion bodies, were similar to the NFTs in the pyramidal neurons of Ammon's horn, which are found most frequently in association with severe neurofibrillary diseases. Under a light microscope, Horoupian's inclusion bodies and PBs could not be differentiated and appeared to be argyrophilic round cytoplasmic inclusions in granular neurons of the dentate fascia. There were, however, ultrastructural differences. Horoupian's inclusion bodies consisted of bundles made up of straight tubules (STs), each about 15 nm in diameter. These bundles were intermixed with a few paired helical filaments which occurred at intervals of about 80 nm. On the other hand, PBs were composed of randomly distributed 15-nm-wide STs, intermixed with a very few fibrillary structures. These fibrils had a periodicity of about 160 nm, and ranged in width from about 15 nm to 30 nm. Horoupian's inclusion bodies associated with DAT and PBs associated with Pick's disease are different in this neuropathological aspect. The NFTs, including Horoupian's inclusion bodies in the dentate fascia in cases of DAT, are considered to be a manifestation of neurofibrillary degeneration.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 77 (1989), S. 654-658 
    ISSN: 1432-0533
    Keywords: Melanotic neuroectodermal tumor ; Immunohistochemistry ; Ultrastructure ; Pineal origin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of a melanotic neuroectodermal tumor arising from pineal region of a 4-year-old girl is presented. The tumor had spread diffusely to the meninges, consistent with malignant behavior. Histologically, the tumor consisted primarily of epithelial elements arranged in tubules, cords and nests separated by fibrous vascular tissue in addition to a small neuroblastomatous focus. Melanin pigment was frequently observed in the epithelial tumor cells, and melanin-laden macrophages were also often observed. No teratoid elements were found. Immunohistochemically, tumor cells were positive for neuron-specific enolase but were nonreactive for S-100 protein, epithelial membrane antigen, glial fibrillary acidic protein, vimentin, α-fetoprotein and human chorionic gonadotrophin. Ultrastructurally, the epithelial nature of the tumor cells could be easily demonstrated. In addition, melanosomes in various stages in maturation were observed, indicating melanogenesis of the tumor. On the basis of the tumor location and the histological similarities previously observed for the fetal pineal body, it is very likely that this melanotic epithelial tumor could have originated from the fetal pineal gland.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 79 (1989), S. 86-93 
    ISSN: 1432-0533
    Keywords: Primary malignant CNS lymphoma ; Ultrastructure ; Intracytoplasmic tubuloreticular, membranous structures ; Intranuclear inclusions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ultrastructural studies of 17 primary malignant CNS lymphomas revealed 6 tumors with abnormal intracytoplasmic and/or intranuclear membranous structures, most frequently, associated with the endoplasmic reticulum or perinuclear envelope. In most cases, tubuloreticular inclusions and paired cisternae were present. Less frequent were accumulation of mictotubules, concentric lamellar bodies, and rod-like or paracrystalline intranuclear inclusions. The specificity and significance of these membranous structures remain questionable because of their frequent occurrence in a variety of normal and pathological conditions. Some of these changes may be considered as cellular reactions to viral infections, others may indicate cellular activity or degeneration.
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  • 14
    ISSN: 1432-0533
    Keywords: 2,4-Dithiobiuret ; Thioimidodicarbonic diamide ; Motor endplate ; Neuromuscular junction ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 2,4-Dithiobiuret was given i.p. to rats for 4 days at a daily dosage of 1 mg/kg and the development of the lesion associated with neuromuscular dysfunction studied in hindlimb lumbrical muscles. The first morphological indication of neurointoxication was the appearance in some motor endplates of masses of branching tubular smooth endoplasmic reticulum (SER) on day 2 which correlated with the initial functional disturbances. By the 3rd day, most motor endplates were distended by accumulations of densecored, lucent and synaptic vesicles, abnormally swollen mitochondria, intermediate filaments and branching, tubular SER. Evidence of collateral axonal sprouting was seen first at this time. On days 4 and 5, many motor endplates were markedly enlarged and showed axoplasmic organelle congestion. A significant increase in synaptic vesicle size was noted at these times in some terminals. Interposition of Schwann cell processes between the pre- and postsynaptic membranes and terminal retraction was now evident. Some intramuscular nerves showed hydropic Schwann cell cytoplasm with separation of the outermost myelin lamellae, mitochondrial swelling and adaxonal vacuoles as early as the 1st day. Proliferation and segregation of SER around central cores of neurofilaments was seen in myelinated nerve fibres and preterminals on the 3rd day. At this and later times accumulations of SER and swollen mitochondria were found at sites of axonal varicosities and at the paranodal constrictions at nodes of Ranvier. These ultrastructural data are discussed with regard to reduced terminal Ca2+ content (demonstrated by oxalate-pyroantimonate cytochemistry) and compared with the sequelae of botulinum intoxication.
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  • 15
    ISSN: 1432-0533
    Keywords: Gangliocytoma ; Ganglioglioma ; Ultrastructure ; Immunohistochemistry ; Neuroendocrine markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We studied five cases of central nervous system neuronal tumor, one gangliocytoma and four gangliogliomas, both ultrastructurally and immuno-histochemically, using antibodies to neuroendocrine markers including tyrosine hydroxylase (TH), serotonin (5HT), somatostatin (SOM), met-enkephalin (MEK), leu-enkephalin (LEK), substance P (SP), gastrin, vasopressin, oxytocin, vasoactive intestinal polypeptide, adrenocorticotropic hormone and calcitonin. In all cases, the presence of dense-core vesicles (60–250 nm) in the neuronal elements was the characteristic ultrastructural finding. Synapses were observed in two cases. Immunohistochemically, variable numbers of neuronal cells showed positive staining for SOM in five cases, TH, MEK and LEK in three cases, and 5HT and SP in one case each. The others were negative. Positive immunoreactivity for multiple markers was shown in all cases. SOM, TH, 5HT and SP were present in the small- to medium-sized cells, while MEK and LEK were almost exclusively confined to the large cells. Our study clearly indicated that these tumors contained neuronal cells which were not homogeneous with regard to neuroendocrine markers.
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  • 16
    ISSN: 1432-0533
    Keywords: Neuronal inclusions ; Leigh disease ; Tropomyosin ; Actin ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A novel type of non-viral cytoplasmic inclusion is described, which was seen in virtually every neuron in the brain and spinal cord of a child with a presumed metabolic disorder whose clinical picture and CNS pathology were compatible with Leigh Syndrome. The ovoid to round inclusions were sharply demarcated, measuring up to 11 μm in diameter. They showed no distinctive staining with a battery of routine histological techniques. The ultrastructural features are unique, comprising non-membrane-bounded aggregates of randomly oriented plate-like structures with parallel linear densities depicting a periodicity of 11–16 nm. Immunocytochemical studies revealed strong staining with antisera to tropomyosin and weaker staining with antisera to actin. There was no reactivity with antibodies against neurofilaments, microtubules and their associated proteins, paired helical filaments, ubiquitin, vinculin or alpha-actinin. It is postulated that the metabolic disorder resulted in a neurodegenerative condition which manifested pathologically with lesions compatible with those of Leigh Syndrome. Associated with the condition was the discrete accumulation of cytoplasmic proteinaceous components, including tropomyosin, in the form of neuronal cytoplasmic inclusions possibly resulting from an alteration of the neuronal cytoskeleton.
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  • 17
    ISSN: 1432-0533
    Keywords: Cerebral hypoxia ; Cerebral ischemia ; Ultrastructure ; Neocortex ; Brain isolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The acute cortical response to surgical brain isolation and subsequent extracorporal normoxic or 30 min hypoxic (PaO2=20 mm Hg) perfusions (hypoxic hypoxia with relative ischemia) was evaluated. Cerebral blood flow, arterial pH and CO2 were maintained constant during both perfusions; only the arterial oxygen content was changed. The isolated brain model used in this and previous investigations produces no qualitative ultrastructural changes in the neocortex following brain isolation and normoxic perfusion. However, the acute cortical structural response to 30 min of hypoxic hypoxia with relative ischemia demonstrated a number of important observations. Hypoxic hypoxia produced ultrastructural responses common to cerebral ischemia such as nuclear chromatin clumping, nucleolar condensation and cytoskeletal breakdown. Although neuronal abnormalities seen after 30 min of hypoxic hypoxia were similar to those acute neuronal changes observed following complete cerebral ischemia without recirculation, they differed three ways: (a) mitochondrial swelling and microvacuolation were observed in many cortical pyramidal neurons. (b) Glycogen particles within astroglial processes were observed even after a 30-min period of hypoxic hypoxia. (c) Perivascular astroglial swelling was minimal despite considerable perineuronal swelling. In contrast, incomplete cerebral ischemia produces mitochondrial changes similar to those in hypoxic hypoxia but also causes the depletion of tissue glycogen and perivascular glial swelling. Thus, hypoxic hypoxia with relative ischemia produces a unique acute ultrastructural response compared to either complete or incomplete cerebral ischemia.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 79 (1989), S. 336-339 
    ISSN: 1432-0533
    Keywords: AIDS ; Cytomembranous inclusions ; Tubuloreticular inclusions ; Ultrastructure ; Peripheral nerve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We report finding tubuloreticular inclusions (TRI) in the endothelial cells of endo- and epineurial vessels in the sural nerve of 11 patients with AIDS. Six patients had a painful peripheral neuropathy, one a non-painful sensory neuropathy, one an acute inflammatory demyelinating polyradiculoneuropathy and one a thalidomide-related neuropathy. Two patients had no clinical evidence of neuropathy. The TRI are not specific to one neuropathy and are unlikely to contribute to the pathogenesis of peripheral nerve syndromes in AIDS.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 79 (1989), S. 168-175 
    ISSN: 1432-0533
    Keywords: Muscular ; Dystrophy ; Ovine ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The initial ultrastructural changes in skeletal myofibers in ovine muscular dystrophy (MD) consisted of focal degeneration of myofibrils and the formation of Z-disc abnormalities, including nemaline rods, in adjacent sarcomeres. Peripheral and central sarcoplasmic masses, which occurred initially in large diameter fibers, contained a mixture of normal organelles and abnormal tubular and fibrillar formations. Vesiculate sarcolemmal nuclei with prominent nucleoli accumulated in central and subsarcolemmal locations in small clusters and short rows. Deformed individual nuclei were sometimes present within nuclear rows. Loss of the myofibrillar mass, increased density of small spherical nuclei, collections of fibrillar and tubular arrays, excessive folding of the sarcolemma and greatly reduced fiber diameter were seen in the end stage of the dystrophic process. Resting satellite cells were present at all stages of lesion development. The morphological progression of the lesions suggested an inherited inability to effectively replace lost myofibrils with ultimate exhaustion of the capacity for repair followed by pathological fiber atrophy.
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  • 20
    ISSN: 1432-072X
    Keywords: Thiothrix sp. ; Beggiatoa sp. ; Sulfideoxidizing ; Polyunsaturated ; Fatty acids ; Inclusions ; Sheath ; Southern California ; Ultrastructure ; Sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microscopic examination of the whitish mat that covered the substrata around subtidal hydrothermal vents at White Point in southern California revealed a “Thiothrix-like” bacterium containing sulfur inclusions as the dominant filamentous form in this microbial community. The matlike appearance developed as a result of the closely-packed manner inwhich the basal ends of the filaments were anchored to the substrate. The dominant phospholipid fatty acids of these filaments (16:0, 16:1w7c, 18:0, 18:1w7c) were similar to those recovered from a sample of Beggiatoa isolated from a spring in Florida. Filaments from both sources contained small quantities of C18 and C20 polyunsaturated fatty acids, as well. A larger but less abundant sheathless, filamentous form, which also contained sulfur inclusions and displayed a cell wall structure similar to a previously described Thioploca strain, also colonized the substrata around the subtidal mat. The preservation methods used in the preparation of thin-sections of the subtidal mat material were found to be inadequate for defining some key cellular structures of the large filaments. Nevertheless, the results demonstrate that the filamentous bacteria comprising the microbial mat in the vicinity of the subtidal vents exhibit some of the features of the free-living filamentous microorganisms found in deep-water hydrothermal areas.
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  • 21
    ISSN: 1432-072X
    Keywords: Gallionella ferruginea ; Thiobacillus ferrooxidans ; Iron bacteria ; Chemolithoautotrophy ; Ultrastructure ; Freeze-etching ; Cell wall organization ; Intracytoplasmic membranes ; Carboxysomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By using sodium thioglycolate to dissolve the high amount of excreted stalk material in axenic cultures of the chemolithoautotrophic iron bacterium Gallionella ferruginea, the ultrastructure of Gallionella cells from pure cell suspensions could be studied without any loss of viability or disturbance by dense ferric stalk fibers, and compared with Thiobacillus ferrooxidans, also grown chemolithoautotrophically with ferrous iron as energy source. Both organisms were chemically fixed or freeze-etched. Particular structural differences between these iron-bacteria could be ascertained. G. ferruginea possesses intracytoplasmic membranes and soluble d-ribulose-1,5-bisphosphate-carboxylase, whereas T. ferrooxidans contains carboxysomes but no intracytoplasmic membranes; Gallionella forms poly-β-hydroxybutyrate and glycogen as storage material; T. ferrooxidans produces only glycogen. Both organisms also differ from each other with respect to the freeze fracture behaviour of the cell envelope layers. Whereas the cells of T. ferrooxidans exhibit a characteristic double cleavage, exposing the plasmic fracture face and exoplasmic fracture face of the outer membrane and cytoplasmic membrane, the exceptionally thin multilayered cell envelope of G. ferruginea revealed a particularly intimate association between the layers, resulting in a visualisation of the supramolecular organisation of only the inner fracture face of the cytoplasmic membrane. The results are discussed predominantly in relation to the extremely distinct environments of both organisms.
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  • 22
    ISSN: 1432-072X
    Keywords: Methanobacterium formicicum ; Formate dehydrogenase ; F420-hydrogenase ; Immunogold ; Ultrastructure ; Methanogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructural locations of the coenzyme F420-reducing formate dehydrogenase and coenzyme F420-reducing hydrogenase of Methanobacterium formicicum were determined using immunogold labeling of thin-sectioned, Lowicryl-embedded cells. Both enzymes were located predominantly at the cell membrane. Whole cells displayed minimal F420-dependent formate dehydrogenase activity or F420-dependent hydrogenase activity, and little activity was released upon osmotic shock treatment, suggesting that these enzymes are not soluble periplasmic proteins. Analysis of the deduced amino acid sequences of the formate dehydrogenase subunits revealed no hydrophobic regions that could qualify as putative membrane-spanning domains.
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  • 23
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 414 (1989), S. 459-464 
    ISSN: 1432-2307
    Keywords: Sebaceous carcinoma ; Parotid gland ; Salivary gland ; Ultrastructure ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sebaceous carcinoma of salivary gland origin is extremely rare and, because of its rarity, the clinicopathological characteristics and the histogenesis are not fully understood. We present a case of sebaceous carcinoma of the parotid gland which brings the total number of reported cases to 22. The tumor showed epithelial cell nests which were mainly composed of sebaceous cells with marked cellular atypia. In most of the nests, glandular spaces lined by ductal epithelium were present. Scattered mucous cells and flattened eosinophilic cells at the periphery of the nests were also seen. Ultrastructural and immunohistochemical observations of the tumour revealed coexistence of sebaceous and glandular differentiations in some tumour cells. Tumour cells with lipid granules often participated in the formation of glandular structures or exhibited intracytoplasmic lumina, and immunohistochemical localization of lactoferrin and secretory component, the functional markers of ductal epithelium of salivary gland, was demonstrated not only in duct-forming tumour cells but also in many sebaceous tumour cells. It seems likely that sebaceous carcinoma originates from pluripotential duct cells which can differentiate into sebaceous, ductal and mucous cells.
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  • 24
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    Virchows Archiv 415 (1989), S. 145-149 
    ISSN: 1432-2307
    Keywords: Paracrystalline inclusion ; Microtubule ; Ciliogenesis ; Gastric ciliated cell ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Unusual electron-dense paracrystalline inclusions were found in metaplastic ciliated cells in the stomachs of three Japanese male patients with gastric carcinoma. These patients had not been given antitumour drugs before surgery and ethrane (enflurane) was used as the anaesthetic. Ciliated cells in the gastric mucosa are found not infrequently in the pyloric glands in association with intestinal metaplasia in elderly Japanese patients. Paracrystalline inclusions were found only in the ciliated cells and never in any other types of gastric mucosal cell. These inclusions were located in the apical portion of the ciliated cells in intimate association with the basal bodies. They consisted of twisted strings about 27 nm wide with a regularly repeated spacing of about 30 nm. On highly magnified electron micrographs, granules about 4 nm in diameter were detected. These paracrystalline inclusions have never been reported previously, although their location in ciliated cells and their morphological characteristics suggest an intimate relationship with the ciliogenesis of metaplastic ciliated cells in the human stomach.
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  • 25
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    Virchows Archiv 414 (1989), S. 113-119 
    ISSN: 1432-2307
    Keywords: Gastric mucosa ; Intestinal metaplasia ; Ciliated cell ; Ciliated metaplasia ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intestinal metaplasia of the gastric mucosa occurs commonly in aged Japanese patients and has been discussed in relation to the high incidence of gastric cancer in Japanese. Ciliated cells in the gastric mucosa have frequently been found in association with intestinal metaplasia in the pyloric gland and rarely in the cardiac gland in many Japanese patients, and exceptionally in one Chinese and in one Swedish patient. Electron microscopic examination of 12 Japanese patients has revealed that these structures are not metaplastic stereocilia, but true cilia. Ciliated cells have been found in the basal part of the gastric glands and never in the surface epithelium. The fine structure of the gastric cilia was almost the same as that of normal respiratory cilia. However, in the gastric cilia, most dynein arms were inconspicuous even after tannic acid fixation, indicating that ciliary beating of the gastric cilia is problematic. Abnormal cilia and basal bodies also were found. Ciliated cells have always occurred in association with intestinal metaplasia, therefore this phenomenon might be a type of metaplasia and is named “ciliated metaplasia” of the gastric mucosa.
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  • 26
    ISSN: 1432-2307
    Keywords: Malignant fibrous histiocytoma ; Ultrastructure ; Enzyme histochemistry ; Immunohistochemistry ; “Fibrohistiocytoid cell”
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ultrastructural, enzyme histochemical and immunohistochemical studies were performed on tissue obtained from eight cases of malignant fibrous histiocytoma (MFH) and five cases of sacral decubitus ulcer. The MFH was composed of two major tumour cell types: fibroblast-like and histiocyte-like cells. Both cell types demonstrated abundant branching, fragmented rough endoplasmic reticulum (rER), many free ribosomes, occasional small mitochondria, an oval, elliptical or irregularly shaped nucleus with one or two prominent nucleoli and often a few dense bodies. However, pseudopodial projections, multivesicular bodies and phagosomes, common histiocyte organelles, were not seen. With little difference between cases or selection sites, the MFH cells reacted to acid phosphatase (AcP) and α-naphtyl butyrate esterase (ANBE) by enzyme histochemistry and with ferritin (Fer), α1-antitrypsin (AT), α1-antichymotrypsin (ACT), fibronectin (FN), HLA-DR, HLA-DP, Leu 10 and OKT 9 in immunohistochemical studies. MFH tumour cells did not immunostain with monocyte/macrophage markers (Leu M1, Leu M3, Mo 1, Mo 2 and Macrophage) although non-neoplastic histiocytes did react to these markers. In addition, granulation tissue, such as that found in sacral decubitus ulcers, was examined and the existence of a specific cell type called the “fibrohistiocytoid (FH) cell” was documented. The FH cell was short, spindle shaped and elliptical. Ultrastructurally, it had fragmented rER distributed in a branching pattern, dispersed free ribosomes, small mitochondria and a few dense bodies, but lacked diverse fused lysosomes and distinct pseudopodial cytoplasmic extensions. The FH cells reacted with AcP, alkaline phosphatase and ANBE but not with peroxidase using enzyme histochemistry and with Fer, AT, ACT, FN, HLA-DR, HLA-DP, Leu 10 and OKT 9 but not with monocyte/macrophage markers, C3d receptor, C3bi receptor in immunohistochemical studies. The FH cells had morphological, enzyme histochemical and immunohistochemical characteristics intermediate between fibroblasts and histiocytes. Similarities between MFH cells and the FH cells seen in chronic inflammation are discussed.
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  • 27
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    Virchows Archiv 415 (1989), S. 21-29 
    ISSN: 1432-2307
    Keywords: Alcoholic liver disease ; Ultrastructure ; Phagocytosis ; Cell shedding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sinusoidal macrophages were studied by light and electron microscopy in 49 liver biopsies from alcohol-abusers with a variety of alcohol-related liver lesions or with near-normal livers. Changes were related to those in nearby hepatocytes. A reduction in the number of macrophages was noted in the more severely damaged livers. Hepatocytes formed blebs at their sinusoidal poles, and these protruded into the space of Disse and into the sinusoidal lumen. It is postulated that reduced phagocytic activity in the livers of patients with severe alcohol-related liver disease leads to increased shedding of hepatocellular material into the circulation. This may promote the development of autoimmune reactions directed against hepatocytes.
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  • 28
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    Archives of dermatological research 281 (1989), S. 35-39 
    ISSN: 1432-069X
    Keywords: Pseudo-Kaposi's sarcoma ; Bluefarb-Stewart syndrome ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An ultrastructural study of the skin lesion of a young patient affected by pseudo-Kaposi's sarcoma of the Bluefarb-Stewart type (BSS) is reported. The neoplasm consisted of a proliferation of vascular structures mostly consisting of a solid bud of endothelial cells surrounded by a thinned and polystratified basement membrane and several pericytes. Both endothelial cells and pericytes were of normal ultrastructural appearance. Intervascular “stromal” cells were few and morphologically identified as macrophages and/or phagocytic fibroblasts. Masses of hemosiderin were detected outside the cells and in the macrophages, endothelial cells, and pericytes. Intracytoplasmatic crystalloid inclusions similar to those found in fetal endothelium and hemangiomas were observed in a few endothelial cells. These findings are different from those of previously reported cases of pseudo-Kaposi's sarcoma and may be helpful in distinguishing Kaposi's sarcoma from BSS. The role of immunodeficiency in the onset of BSS is discussed.
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  • 29
    ISSN: 1432-2013
    Keywords: Exercise ; Heart ; Mitochondria ; Oxygen uptake ; Respiration ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The relationship between maximal oxygen consumption rate ( $$\dot V{\text{O}}_{{\text{2max}}}$$ ) and mitochondrial content of skeletal muscles was examined in horses and steers (n=3 each). Samples of the heart left ventricle, diaphragm,m. vastus medialis, m. semitendinosus, m. cutaneous thoracicus andm. masseter, as well as samples of muscles collected in a whole-body sampling procedure, were analyzed by electron microscopy. $$\dot V{\text{O}}_{{\text{2max}}}$$ per kilogram body mass was 2.7× greater in horses than steers. This higher $$\dot V{\text{O}}_{{\text{2max}}}$$ was in proportion to the higher total volume of mitochondria in horse versus steer muscle when analyzed from the whole-body samples and from the locomotor muscle samples. In non-locomotor muscles, total mitochondrial volume was greater in horses than steers, but not in proportion to their differences in $$\dot V{\text{O}}_{{\text{2max}}}$$ . The $$\dot V{\text{O}}_{{\text{2max}}}$$ of the mitochondria was estimated to be close to 4.5 ml O2·ml−1 mitochondria in both species. It is concluded that in a comparison of a highly aerobic to a less aerobic mammalian species of similar body size, a higher oxidative potential may be found in all muscles of the more aerobic species. This greater oxidative potential is achieved by a greater total volume of skeletal muscle mitochondria.
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  • 30
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    Experimental brain research 76 (1989), S. 12-20 
    ISSN: 1432-1106
    Keywords: Distribution ; Ultrastructure ; Biopsy ; Catecholamines ; Interneurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In freshly fixed biopsies of human cerebral cortex obtained at surgery, immunocytochemical staining with antibodies against tyrosine hydroxylase (the rate limiting biosynthetic enzyme for catecholamines) revealed, in addition to a dense axonal plexus, a population of immunoreactive cell bodies. The neuronal nature of these cells was ascertained by: i) the presence of a rich rough endoplasmic reticulum in the cell body and of synapses on the cell body and dendrites, and ii) the demonstration of the lack of reactivity with the astroglial marker, glial fibrillary acidic protein, in the tyrosine hydroxylase-immunoreactive cells. The tyrosine hydroxylase-immunoreactive neurons were found in all areas of cortex sampled, and were located almost exclusively in the infragranular layers. Most tyrosine hydroxylase-immunoreactive cells were bipolar and were vertically oriented, but a few had a multipolar or horizontal dendritic arbor. The dendrites of these cells were varicose and aspiny, and the axons were very thin. Tyrosine hydroxylase-immunoreactive neurons were reported to be present transiently in the developing mammalian cerebral cortex and only recently in cerebral cortex of mature mammalian brains. Internuncial neurons in the human cerebral cortex containing a catecholamine synthesizing enzyme would be significant, in particular considering that catecholamines are likely to be involved in some major mental disorders.
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  • 31
    ISSN: 1432-1106
    Keywords: Calcitonin gene-related peptide (CGRP) ; Bed nucleus of the stria terminalis ; Central nucleus of the amygdala ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Light and electron microscopic analysis of calcitonin gene-related peptide (CGRP)-like immunoreactive (LI) terminals in the bed nucleus of the stria terminalis (BST) and the central nucleus of the amygdala (Ce) was carried out using the peroxidase-antiperoxidase method. CGRP-LI fibers were densely distributed in the dorsal subdivision of the lateral BST (BSTL) and the lateral and lateral capsular subdivisions of the Ce, where the CGRP-LI terminals formed symmetrical and asymmetrical axo-dendritic, and symmetrical axosomatic synapses. One of the most characteristic features of the CGRP-LI terminals was the presence of large, long boutons, each of which surrounded a cell soma and made many synaptic contacts. These findings suggest that CGRP exerts a significant influence on neurons in the BSTL and Ce.
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  • 32
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    European archives of oto-rhino-laryngology and head & neck 246 (1989), S. 169-172 
    ISSN: 1434-4726
    Keywords: Tympanic membrane ; Ultrastructure ; Sensory receptors ; Nerve endings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Encapsulated nerve endings were found in both the subepidermal connective tissue and the lamina propria of a human tympanic membrane. The structure of the corpuscles was round or oval and contained a number of axon terminals with mitochondria and Schwann cell processes. Amorphous materials were present in the intercellular space. These features appear to be advantageous in transmitting mechanical forces on the capsule to the axon terminals and are comparable to the function of a mechanoreceptor. Resultant changes in the shape and stiffness of the tympanic membrane as the result of its dislocation indicate similar changes in the pressure on the corpuscle. The arrangement of the sensory corpuscles suggests that they may play a role in detecting pressure changes in the middle ear cavity.
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  • 33
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    European archives of oto-rhino-laryngology and head & neck 246 (1989), S. 56-60 
    ISSN: 1434-4726
    Keywords: Carbonic anhydrase ; Vestibular organ ; Guinea pig ; Histochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Carbonic anhydrase activity was demonstrated cytochemically on an ultrastructural level in the vestibular end organs of the guinea pig. Reaction product was found in the dark cells, transitional cells, cells of the planum semilunatum and supporting cells. In the dark cells, reaction product was observed in the cytoplasm as well as in the basal infoldings. Reaction product was also observed in the basal infoldings of the transitional cells and the cells of the planum semilunatum. The globular structures inside the supporting cells, transitional cells and the cells of the planum semilunatum were also surrounded by the reaction product. These findings suggest that carbonic anhydrase may have different functions, such as water and ion transport, respiration, nutrition and calcium carbonate deposition in the vestibular end organs.
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  • 34
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    Sexual plant reproduction 2 (1989), S. 193-198 
    ISSN: 1432-2145
    Keywords: Polymorphism ; Ultrastructure ; Pollen grains ; Canna indica L ; Tannin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Our investigations on Canna indica L. indicate that the pollen of this species is polymorphic: there are two types of pollen — a larger type and a comparatively smaller type. Transmission electron microscopy (TEM) revealed the presence of small vacuoles containing tannic substances in the generative cell (GC) of the larger grains: the GC of the mature grain contained a higher quantity of tannins than the GC of the immature grain. Mitochondria, lipid bodies, rough endoplasmic reticulum (RER) and microtubular bundles were present in the cytoplasm of the GC. Numerous mitochondria, lipid bodies and plastids were also present in the vegetative cell (VC), with the mitochondria clustered around the vegetative nucleus. The plastids were observed to be associated with the RER cisterns. During the maturation process, the number of starch grains contained in the plastids decreased.
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  • 35
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    Sexual plant reproduction 2 (1989), S. 154-166 
    ISSN: 1432-2145
    Keywords: Helianthus annuus ; Unfertilized ovule culture ; Parthenogenesis ; Ultrastructure ; Proembryo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Electron microscope studies have been conducted on the parthenogenesis induced by in vitro culture of unfertilized ovules of sunflower (Helianthus annuus). In comparison with the state of the egg prior to inoculation, some eggs 5 days after culture show striking ultrastructural changes, which include, among others, nuclear migration, an increase in the number and activity of the organelles, a loss of polarity and wall formation at the chalazal end of the cell. Most of these changes are similar to those that occur normally in the zygote, indicating that parthenogenic development has been triggered in these eggs. Such eggs have been termed activated and are presumed to be capable of undergoing parthenogenesis. The parthenogenic proembryos which result share some features in common with zygotic proembryos. In addition, some parthenogenic proembryos exhibit unique properties not found in zygotic proembryos. These include embryos that consist of two parts differing markedly in density, an inversion of polarity, the frequent occurrence of autophagic vacuoles, the thickening of cell walls, a centripetal growth mode of wall formation, the appearance of an incomplete cell wall, free nuclear division, amitosis and degeneration. We believe that these ultrastructural peculiarities are the effects of in vitro culture.
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  • 36
    ISSN: 1435-5604
    Keywords: Intercellular communication ; Gap junction ; Calcification ; Collagen gel ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To analyze the mechanism of initiation of cell-mediated calcification in hard tussue and its relationship to the frequency of gap junctions, enzymatically isolated cells from fetal rat calvaria cultured in collagen gels were observed ultrastructurally over a time course. Calcification was observed at 2–3 weeks after the initiation of culture when the seeding cellularity and the concentration of β-glycerophosphate were sufficiently high. In the collagen gels, round cells (R), spindle or stellate cells (S), and fat cells (F) were characterised morphologically. The ultrastructural features of initial calcification could be classified into 4 subtypes: 1) a large mass greater than 10 µm in diameter (Type I), 2) deposition associated with dead R cells or matrix vesicles (Type II), 3) intracellular deposition (Type III), and 4) other than Types I–III (Type IV). Type II was the most frequent (44.5%) and Type III was the least (6.8%). Gap junction was observed frequently between 1) R cells, 2) S cells, 3) between R cells and S cells. The frequency of gap junctions in collagen gels decreased statistically (X2-test; p〈0.001), when calcification was initiated. This cell culture system can be regarded as a useful model to analyze the initiation of cell mediated calcification in hard tissue. Gap junctions might function in cell communication and a decrease in their numbers could lead to cell death and, subsequently to calcification.
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  • 37
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    Journal of Chemometrics 3 (1989), S. 431-441 
    ISSN: 0886-9383
    Keywords: Resolution of mixtures ; Excitation-emission matrices ; Eigenanalysis ; Wavelength component vectorgram ; Total luminescence spectroscopy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We consider the problem of resolving the total luminescence spectra of two-component mixtures. Non-negativity of the constituent spectra is commonly used as a criterion to accomplish this resolution, but its application seldom leads to unique answers. Sometimes, the condition must be relaxed because no solution satisfying non-negativity exists. In these cases judgments must be made concerning which parts of the spectra will be allowed to go negative and by how much.The wavelength component vectorgramn (WCV) is presented here as a tool for assisting the experimenter in making these judgments. Even when non-negative resolutions exist, it may happen that resolutions with slight negative elements will more closely match the spectra of the pure constituents. The WCV can also be used as a tool for detecting these cases. The methodology is illustrated with real data from a two-component mixture.
    Additional Material: 3 Ill.
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  • 38
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    Journal of Chemometrics 3 (1989), S. 453-453 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 39
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    Journal of Chemometrics 3 (1989), S. 451-452 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 40
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    Journal of Chemometrics 3 (1989), S. 443-449 
    ISSN: 0886-9383
    Keywords: Multicomponent analysis ; Iterative refinement ; Simplex method ; Condition numbers ; Linear programming ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Concentration estimates of components present in a sample mixture can be obtained using matrix mathematics. In the past, the condition number of the calibration matrix has been used to give an amplification factor by which uncertainties in data can work through to errors in the concentration estimates. This paper explores an additional interpretation of condition numbers with regards to significant figures and rounding errors. A procedure is suggested which will always give the most accurate concentration estimates provided the calibration matrix is not too ill-conditioned. Condition numbers have also been used by analytical chemists to discuss the error bounds for concentration estimates. Unfortunately, only one representative error bound can be approximated for all the components. This paper will show how to compute bounds for individual concentration estimates obtained as solutions to a system of m equations and n unknowns. The procedure is appropriate when calibration data and sample responses are inaccurate.
    Additional Material: 1 Ill.
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  • 41
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    Journal of Chemometrics 3 (1989) 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 42
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    Journal of Chemometrics 3 (1989), S. 21-32 
    ISSN: 0886-9383
    Keywords: Kalman filter ; Multicomponent analysis ; Fluorescence spectral shifts ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of peak shifts on the performance of a Kalman filter multicomponent analysis algorithm has been investigated. A series of Gaussian test systems were employed to characterize the concentration estimation errors and the morphology of the on-line residuals (the innovations sequence). Both forward and reverse filters were used in the generation of the innovations sequences. It was found that the difference between the forward and reverse innovations sequences gave an accurate indication of the direction and magnitude of the peak shift. A series of overlapped two-component systems were also investigated. Again, a correlation between the difference innovations and the degree of the response shift was observed. The behavior of the Kalman filter in fitting the shifted fluorescence emission spectrum of benzo[a]pyrene was also examined. The response for benzo[a]pyrene in cyclohexane solution was compared to that obtained on the surface surface of a reversed phase thin layer chromatography plate. A red shift of 4 nm was detected for the surface spectrum by observing the difference innovations sequence. This approach holds promise for correction of response shifts in multicomponent systems.
    Additional Material: 7 Ill.
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  • 43
    ISSN: 0886-9383
    Keywords: Principal component analysis ; Factor analysis ; Singular value decomposition ; Eigenvalue analysis ; Multivariate analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fisher variance ratio tests are developed for determining (1) the number of statistically significant abstract factors responsible for a data matrix and (2) the significance of target vectors projected into the abstract factor space. F-tests, developed from the viewpoint of vector distributions, are applied to various data sets taken from the chemical literature.
    Additional Material: 3 Tab.
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  • 44
    ISSN: 0886-9383
    Keywords: Parameter estimation ; Cyclic voltammetry ; Quasi-reversible electron transfer reactions ; Cerium (IV) bis(octaethylporphyrinate) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Values of the peak potential, the peak current function and the peak potential difference are extracted from simulated cyclic voltammograms of a quasi-reversible electron transfer reaction. Variations of the feature values are described by empirical functions of the model parameters α (transfer coefficient) and ψ′ (dimensionless form of the heterogeneous electron transfer rate constant ks) using multiple linear regression. These functions are used to determine the system parameters α and ks from test data sets of feature values. The predictive power of the features is discussed. It is shown that several features can be used simultaneously in the analysis. Also, α, ks, the formal potential E0 and the diffusion coefficient D can be estimated simultaneously. Experimental data from the metal-centered one-electron reduction of cerium (IV) bis(octaethylporphyrinate), Ce(OEP)2, are analyzed using the technique, and values of the system parameters for this electrochemical reaction are determined.
    Additional Material: 7 Ill.
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  • 45
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 46
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    Journal of Chemometrics 3 (1989), S. 547-547 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 47
    ISSN: 0886-9383
    Keywords: Evolving factor analysis ; Flow injection analysis ; Self-modeling curve resolution ; Bismuth chloride complexes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Evolving factor analysis is used to estimate the concentration profiles and spectra of Bi3+ and the bismuth chloride complexes BiC12+ through BiCl63- formed by injection of bismuth perchlorate into a flowing stream of 1·0 mol 1-1 HCl. The estimated spectra compare favorably with previously published spectra of the complexes.
    Additional Material: 6 Ill.
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  • 48
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    Journal of Chemometrics 3 (1989), S. 463-475 
    ISSN: 0886-9383
    Keywords: Classification ; Discriminant analysis ; Principal components ; Biased estimates ; Cross-validation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Classification and regression techniques are among the most used tools by chemometricians. With classification, the two classic methods are discriminant analysis and SIMCA. In this paper we discuss the connection between these two methods and introduce two new ones of the same family: DASCO (discriminant analysis with shrunken covariances) and RDA (regularized discriminant analysis). We demonstrate on both simulated and real data sets that their performance is superior to the old favorites. This is especially true in small-sample/high-dimension settings typical in chemistry.
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  • 49
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    Journal of Chemometrics 3 (1989), S. 493-498 
    ISSN: 0886-9383
    Keywords: Rank annihilation ; Generalized rank annihilation method ; Generalized eigenproblem ; Calibration ; Spectral interferents ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved algorithm for the generalized rank annihilation method (GRAM) is presented. GRAM is a method for multicomponent calibration using two-dimensional instruments, such as GC-MS. In this paper an orthonormal base is first computed and used to project the calibration and unknown sample response matrices into a lower-dimensional subspace. The resulting generalized eigenproblem is then solved using the QZ algorithm. The result of these improvements is that GRAM is computationally more stable, particularly in the case where the calibration sample contains chemical constituents not present in the unknown sample and the unknown contains constituents not present in the calibration (the most general case).
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  • 50
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    Journal of Chemometrics 3 (1989), S. 477-491 
    ISSN: 0886-9383
    Keywords: Principal components analysis ; Cross-validation ; Procrustes rotation ; Variable selection ; Quality control ; Aviation turbine fuel ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Given a set of test criteria that determine a quality specification, the question often arises whether any of the tests are redundant because of intercorrelations Simple selection of tests on the basis of partial correlations with the other tests is rejected on the basis that the random error in the data may be causing spurious correlations.One method is to use cross-validation to define the systematic principal components and examine the correlation structure in this reduced space. It is shown that the presence of principal components dominated by individual tests (‘variable specific’ PCs), which are indicated by cross-validation as being non-systematic, must be taken into account. Having defined the dimensionality, a variable reduction method based on Procrustes rotation selects subsets of tests that preserve the structure of the samples in multivariate space. This is an attractive proposition in the context of maintaining a quality control specification. It is also shown that the variable reduction technique can be used to aid the identification of the true dimensionality of the data space. This approach is applied to a number of routine tests carried out on aviation turbine fuel.
    Additional Material: 10 Ill.
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  • 51
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    Journal of Chemometrics 3 (1989), S. 499-509 
    ISSN: 0886-9383
    Keywords: Optimization ; Response surface ; PLS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The paper presents a procedure to obtain response surfaces with non-designed data. The method is based on PLS modelling of the expanded X-matrix followed by transformation of the PLS loadings into polynomial coefficients and detection of the co-ordinates of the best response within the experimental domain. The results are presented both graphically and numerically. The procedure is validated on an optimization study of the yield of an organic reaction.
    Additional Material: 4 Ill.
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  • 52
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    Journal of Chemometrics 3 (1989), S. 3-20 
    ISSN: 0886-9383
    Keywords: Algorithm ; Computer program ; Data modeling ; Latent variables ; Multiblock ; Multivariate ; PLS ; Process model ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The details of a general multiblock partial least squares (PLS) algorithm based on one originally presented by Wold et al. have been developed and are completely presented. The algorithm can handle most types of relationships between the blocks and constitutes a significant advancement in the modeling of complex chemical systems. The algorithm has been programmed in FORTRAN and has been tested on two simulated multiblock problems, a three-block and a five-block problem. The algorithm combines the score vectors for all blocks predicting a particular block into a new block. This new block is used to predict the predicted block in a manner analogous to the two-block PLS. In a similar manner if one block predicts more than one other block, the score vectors of all predicted blocks are combined to form a new block, which is then predicted by the predictor block as in the two-block PLS. Blocks that both predict and are predicted are treated in such a way that both of these roles can be taken into account when calculating interblock relationships. The results of numerical simulations indicate that the computer program is operating properly and that the multiblock PLS produces meaningful and consistent results.
    Additional Material: 9 Tab.
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  • 53
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    Journal of Chemometrics 3 (1989), S. 97-98 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 54
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    Journal of Chemometrics 3 (1989) 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 55
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    Journal of Chemometrics 3 (1989), S. 100-100 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 56
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    Journal of Chemometrics 3 (1989), S. 375-395 
    ISSN: 0886-9383
    Keywords: Non-parametric method ; Pattern recognition ; Classification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A non-parametric method for supervised pattern recognition is presented. The method is of the class modelling type, meaning that a classification rule is developed for each class, using the dissimilarities between the objects of the class. The dissimilarities between the objects within a class are related to the distances between all pairs of training objects. As distance metric, a measure is proposed that takes the correlation between the interval-scale variables into account, and that moreover can be used for mixed types of variables. The classification rule is based on the construction of a boundary in the measurement space. For the determination of the class boundary, several strategies are proposed and compared.The performance of the technique is evaluated on the basis of several data sets. Comparison with the class modelling technique UNEQ shows its usefulness for practical application.
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  • 57
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    Journal of Chemometrics 3 (1989), S. 409-418 
    ISSN: 0886-9383
    Keywords: Multivariate calibration ; Singular value decomposition ; Regression diagnostics ; Collinearity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Care is required for multicomponent analysis if misleading results are to be avoided. The problem of ill-conditioned calibration matrices is of primary concern. This type of numerical instability is represented as spectral overlap of calibration spectra. Depending on the degree of spectral overlap, the sample concentration estimates can be severely affected. A practical statistical procedure is discussed which tests for the presence of spectral overlap among the pure-component spectra and simultaneously assesses the degree that concentration estimates may be degraded. Guidelines are developed to ascertain how much departure from spectral orthogonality is acceptable.
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  • 58
    ISSN: 0886-9383
    Keywords: NIR reflectance ; Multivariate analysis ; Principal component analysis ; Stepwise multiple linear regression ; Silage quality ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Calibrations to predict crude protein (CP) and in vitro dry matter digestibility (IVDMD) in dried grass silage from reflectance data collected at 19 wavelengths on an InfraAlyzer 400R have been developed using stepwise multiple linear (SML) and principal component (PC) regression techniques. A direct comparison of the efficacy of each multivariate technique in this applications has been possible by using identical calibration development and evaluation sample sets. The effect of two data transformation steps prior to PC regression was also investigated. PC regression of raw reflectance data yielded no significant improvement in the standard errors of prediction (SEP) for CP and IVDMD over those obtained by SMLR, viz. 0·61 vs 0·63 and 2·9 vs 3·0 respectively. Computation time for development and evaluation of the PC regression equation was less than for selection of the best SMLR equation, and PCR equations may be more robust. Data transformation to reduce granularity effects prior to PCR did not produce any improvement in predictive accuracy for either IVDMD or CP.
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  • 59
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    Journal of Chemometrics 3 (1989), S. 453-453 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 60
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    Journal of Chemometrics 3 (1989), S. 601-608 
    ISSN: 0886-9383
    Keywords: Gas phase flow injection analysis ; Membrane-differentiated analysis ; Multicomponent determinations ; Successive linear regression ; Successive regression in fiduciary region ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A membrane-discriminated gas phase analyzer is proposed for multicomponent determinations. Nitrogen gas flows countercurrent through outer and inner channels in a tube-in-tube arrangement. The only communication between the two channels occurs through a 500 μm aperture covered by a porous PTFE membrane. A mixture of organic compounds (up to four components) is injected into the inner channel by a heated backflushed injector and the sample components diffusing into the outer channel are monitored by a flame ionization detector (FID). A calibration set, consisting of pure components, binary, ternary and quaternary mixtures (a total of 64 samples), provides the known data base: temporal profiles of the FID output as a function of sample composition. Although the overall response behavior is not a linearly additive function of individual analyte concentrations, the use of successive inverse multiple linear regression (while continually altering the choice of the calibration samples considered for the forward regression, on the basis of the most recent values of the predicted unknown sample composition) is shown to yield analytical results for unknown samples that are in good agreement with their true values.
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  • 61
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 62
    ISSN: 0886-9383
    Keywords: Fuzzy set theory ; Classification ; Data reduction ; Historical laboratory data ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A computer program (FEA) is presented for processing historical laboratory data. It performs on a list of sample entries stored in a laboratory information management system. Using an algorithm which is based on fuzzy set theory, FEA classifies the entries into a limited number of clusters called sample types. The classification is fully user-defined. The program transforms the historical data into a representation which is more suitable for studying the performance of the laboratory or which can be used as preparation for a simulation project.
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  • 63
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    Journal of Chemometrics 3 (1989), S. i 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 64
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    Journal of Chemometrics 3 (1989), S. 329-342 
    ISSN: 0886-9383
    Keywords: Calibration ; Robust regression ; Iteratively reweighted least squares ; M-estimator ; Monte Carlo simulations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By means of Monte Carlo simulations a comparison has been made between ordinary least squares regression and robust regression. The robust regression procedure is based on the Huber estimate and is computed by means of the iteratively reweighted least squares algorithm. The performance of both procedures has been evaluated for estimation of the parameters of a calibration function and for determination of the concentration of unknown samples. The influence of the distributional characteristics skewness and kurtosis has been studied, and the number of measurements used for constructing the calibration curve has also been taken into account. Under certain conditions robust regression offers an advantage over least squares regression.
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  • 65
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    Journal of Chemometrics 3 (1989), S. 343-357 
    ISSN: 0886-9383
    Keywords: Principal components regression ; Factorial design ; Hypothesis testing ; Assay validation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A validation protocol for multicomponent spectroscopic assays based on principal components regression is described. Factorial design and hypothesis tests are used to establish the linearity and absence of interaction between components in the regression model. Testing considers multiple response variables simultaneously so that correlation between residuals is properly treated. Assay reproducibility and sensitivity to related substances are evaluated.
    Additional Material: 2 Ill.
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  • 66
    ISSN: 0886-9383
    Keywords: Abstract factor analysis ; Target transformation factor analysis ; Signal-to-noise ratios ; Canonical variates analysis ; 13C NMR spectroscopy ; Mixture constituent identification and estimation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of experimental error in analysis of mixture experiments by abstract factor analysis or target transformation factor analysis is considered. The theoretical implications of using signal-to-noise ratios (as weights) or canonical variates analysis to reduce the level of imbedded error in the factor model are examined. The approach is illustrated by application to 13C NMR spectra of lubricant basestock mixtures.
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  • 67
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    Journal of Chemometrics 3 (1989), S. i 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 68
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    Journal of Chemometrics 3 (1989), S. 419-429 
    ISSN: 0886-9383
    Keywords: Image analysis ; Chemical imaging ; Multivariate image analysis ; Image analysis for non-imaging techniques ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Images can contain chemical information and many chemical methods can generate image data. For an efficient extraction of chemical data from images, data analysis techniques are necessary. It is a great advantage to be able to work on multivariate images. Many imaging techniques allow the extraction of chemical information. Inorganic analytical chemistry seems to have the longest tradition here, but organic chemistry and biochemistry may soon be catching up. Also large data arrays from non-imaging techniques can be combined with image analysis in a useful way, provided certain conditions are fulfilled.
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  • 69
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    Journal of Chemometrics 3 (1989), S. 537-540 
    ISSN: 0886-9383
    Keywords: Cluster analysis ; Display ; Interlaboratory test ; Ultrametrics ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ultrametric inter-object distances found by hierarchical clustering may be used to generate and appropriate constellation of points in a plane. A configuration of points which reproduce the ultrametric distances in a low-dimensional space as closely as possible can be found by Torgerson's method of multidimensional scaling. The resulting display supports the cognition of clusters very well, and for this purpose it seems to be superior to, for instance, the frequently applied principal components display. In certain situations dedrograms are expected to become simpler to interpret when such complementary ‘cluster display’ is also consulted. An example from analytical chemistry is presented.
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  • 70
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 71
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 72
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    Journal of Chemometrics 3 (1989), S. 544-545 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 73
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    Journal of Chemometrics 3 (1989) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 74
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    Journal of Chemometrics 3 (1989), S. i 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 75
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    Journal of Chemometrics 3 (1989) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 76
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    Journal of Chemometrics 3 (1989), S. i 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 77
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    Journal of Chemometrics 3 (1989), S. 549-568 
    ISSN: 0886-9383
    Keywords: Multivariate calibration and quantitation ; Factor analysis ; Experimental design ; Sample selection ; Statistical inference ; Wavelength selection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: One of the major application areas of factor analysis, multivariate calibration and quantitation, is covered in this review. The algorithms, methodologies and applications covered include principal component regression, target transformation factor analysis, singular value decomposition and rank annihilation factor analysis. Many important areas of research having relevance to multivariate calibration and quantitation problems are also covered in this review, including background correction, measurement error, rank determination, cross-validation, figures of merit, detection of invalid samples, experimental design, sample selection, statistical inference and wavelength selection.
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  • 78
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    Journal of Chemometrics 3 (1989), S. 569-577 
    ISSN: 0886-9383
    Keywords: ATP hydrolysis ; Regression analysis ; Model discrimination ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Data of the hydrolysis of adenosine 5′-triphosphate have been re-evaluated using a computer program that numerically integrates the differential rate equations within a routine that optimizes rate coefficients given a suitable model and concentration versus time data.The model is tested by calculation of Hamilton R-values, the Fisher F-statistic, a sensitivity analysis, the standard errors on the rate coefficients and by constructing contour maps of the objective function versus two rate coefficients.An optimization using only phosphate concentration data cannot distinguish between a model in which adenosine 5′-monophosphate is formed predominantly directly with a molecule of pyrophosphate, and one in which it is formed via adenosine 5′-diphosphate. A more accurate set of rate coefficients is calculated from existing data and the relative importance of the two paths determined.
    Additional Material: 5 Ill.
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  • 79
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    Journal of Chemometrics 3 (1989), S. 579-588 
    ISSN: 0886-9383
    Keywords: Response surface methodology ; Principal components analysis ; Optimization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Analysis of multivariate response data by modelling the principal components of the response has been applied to two sets of data. In both cases principal components analysis revealed the relationships among the response variables and exploited them to simplify the problem of modelling and optimizing the multivariate response. The models and optima obtained from the principal components compared favourably with the individual models and simultaneous optima.
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  • 80
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    Journal of Chemometrics 3 (1989), S. 589-600 
    ISSN: 0886-9383
    Keywords: Discriminant analysis ; Principal components ; Canonical variates ; Multivariate analysis of variance ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When the number of variables exceeds the number of samples, one method of multivariate discrimination is to use principal components analysis to reduce the dimensionality and then to perform canonical variates analysis (PC-CVA). This paper proposes an alternative approach in which discriminant analysis is carried out by a weighted principal component analysis of the group means (DPCA). This method does not require prior data reduction and produces discriminant factors that are orthogonal in the original data space.The theory and performance of the two methods are compared. Although the individual factors of DPCA are found to be less discriminating than PC-CVA, the overall discrimination, calculated by multivariate analysis of variance, and the predictive value, estimated by the leaving-one-out error rate, are broadly comparable.
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  • 81
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    Journal of Chemometrics 3 (1989), S. 609-609 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 82
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    Journal of Chemometrics 3 (1989), S. 511-527 
    ISSN: 0886-9383
    Keywords: Expert system ; Time series analysis ; Autocorrelation ; Laboratory input signals ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An expert system is presented for automated time series analysis of laboratory sample input signals. The system, AUTOCORR, builds a model of the time series by identifying the processes that are present. These are an uncorrelated random process and, underlying this, possibly one or more of the following: a first-order autoregressive process, a trend and a periodic process. AUTOCORR has a knowledge base of 44 rules and 41 facts for this purpose. The employed shell, INFER, allows the use of algorithmic procedures. Elaborate tests with simulated signals show that AUTOCORR has a very low false positive score and is successful in describing time series for laboratory simulation models.
    Additional Material: 11 Ill.
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  • 83
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    Journal of Chemometrics 3 (1989), S. 529-536 
    ISSN: 0886-9383
    Keywords: Calibration ; Inverse estimator ; Classical estimator ; Mean square error (MSE) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A brief review of the literature on point estimators in linear calibration problems is undertaken. Supportive evidence for the relative merits of the classical and inverse regression models, drawn in general from the classical inferential and Bayesian approaches, is considered and the criteria for comparison of the estimators are discussed with respect to their suitability for certain classes of problems. the performance of the estimators is assessed with respect to determining the current value of ‘x’, the percentage concentration of administered drug levels in blood in this example. No single ‘best’ method of estimation appears to hold for all values of the unknown concentration when performance is assessed by criteria based on the mean square error (MSE). However, the inverse estimator would appear to be superior to the classical for those values of unknown X close to x̄.
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  • 84
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    Journal of Chemometrics 3 (1989), S. 1-1 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 85
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    Journal of Chemometrics 3 (1989), S. 33-48 
    ISSN: 0886-9383
    Keywords: Higher-order data arrays ; Dimensionality ; Data modelling ; Classification ; Discrimination ; Correlation ; Regression ; Systematics of data analysis ; Opportunities for future developments ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A scaffold for detailed understanding of the concept ‘dimensionality’ in data analysis is furnished by a systematic classification of higher-order data array configurations. Three major types of problem formulation in multivariate data analysis can be characterized for relevant data classes: 1data description (intra-class data structure modelling of inter-object and inter-variable relationships)2classification (inter-class discrimination)3correlation, regression (inter-variable relationships).The relationship between these three categories of data analytical problem formulation and the fundamental data array classification is exposed. These relations are augmented to include the general case of data arrays of order R, and R-way data analysis with the use of bilinear projections is presented. Based upon this, some possible directions for the future development of data analysis may be imagined.
    Additional Material: 8 Ill.
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  • 86
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Two-sector linked-scan analysis of an unpurified proteolytic digest of a pyruvate decarboxylase enzyme (60 000 Da) has allowed the discovery and assignment of an amino-terminal post-translational modification and processing event. A difference in amino acid sequence from that predicted by a recently published nucleotide sequence has also been found. These results illustrate both the use and considerable potential of linked-scan methods for the analysis of complex biopolymer mixtures.
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  • 87
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 68-71 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Product ion spectra derived from molecule ions as the precursor ions for 14 alkylbenzenes have been studied under electron ionization and methane chemical ionization. The data have provided a satisfactory screening method for both detection and confirmation of such compounds at low parts per million levels.
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  • 88
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 138-140 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Product-ion spectra derived from both protonated and hydride-abstracted molecules of long chain esters have revealed an unusual homologous series of ions which suggest a cyclization mechanism to form stabilized bicyclodecenes or bicyclononenes.
    Additional Material: 2 Ill.
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  • 89
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 155-159 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A new time-of-flight mass analyser compatible with conventional continuous ionization methods is described. A mass resolution at m/z 2000 of m/Δm〉2000 (50% valley) is predicted for the instrument which is presently being prototyped. Sensitivity advantages over scanning instruments are also predicted for this instrument.
    Additional Material: 4 Ill.
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  • 90
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 170-170 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 91
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 79-84 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Capabilities of high resolution chromatography/tandem mass spectrometry for quantitation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo furans have been investigated with a hybrid instrument. Selected-transition monitoring procedures, collision energy and collision gases have been optimized for maximum sensitivity. The results are compared with those obtained by high resolution chromatography/high resolution mass spectrometry.
    Additional Material: 7 Ill.
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  • 92
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    Rapid Communications in Mass Spectrometry 3 (1989), S. ii 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 93
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: An on-line coaxial continuous-flow capillary-zone electrophoresis/fast-atom bombardment mass spectrometry (CZE/FAB-MS) interface is described. This interface is shown to be capable of acquiring mass spectra in an online fashion from low femtomole amounts of peptides while maintaining high (hundreds of thousands of plates) electrophoretic separation efficiencies. Active electrophoretic transport of the analytes directly to the FAB probe tip obviates the need for a transfer line from the end of the CZE capillary to this point, and thereby precludes the zone broadening that would otherwise occur both within such a transfer line and in the connections between the CZE column and the transfer line. The capability of acquiring an on-line tandem mass spectrometry (MS/MS) spectrum of an electrophoretically separated analyte using this interface is also demonstrated.
    Additional Material: 11 Ill.
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  • 94
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    Rapid Communications in Mass Spectrometry 3 (1989), S. iii 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 95
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 96
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 212-216 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Collisionally activated decomposition spectra derived from normal nucleosides and nucleotides have been studied using a four-sector tandem mass spectrometer. The selectivity for a precursor ion has been improved by the use of the first two sectors as a double-focusing mass spectrometer, and the mass resolution of daughter spectra has been enhanced using the next two sectors as a second double-focusing mass spectrometer. Reliable and reproducible data with respect to the structure of nucleosides and nucleotides have been obtained.
    Additional Material: 6 Ill.
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  • 97
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 222-224 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The fragmentation of some carbamoyl- and thiocarbamoylcyclohexanones under electron ionization has been investigated by means of high- and low-resolution mass spectrometry and deuterium labelling. Some characteristic fragmentation processes observed in the mass spectra of thiocarbamoylcyclohexanones indicate that both keto and enol forms of their molecular ions exist in the gas phase. The fragmentation data for carbamoylcyclohexanone show that the keto form is largely predominant in the keto-enol tautomeric equilibrium.
    Additional Material: 1 Ill.
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  • 98
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 217-221 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Sequential daughter-ion-scanning analyses of small peptides have been performed using a hybrid tandem instrument of BEqQ configuration. Precursor ions are selected by B and allowed or induced (by high-energy collisional activation) to decompose in the region preceding E. Decoupling of E from the accelerating voltage permits the selection of the first-generation daughter ion whilst retaining appropriate float voltages for the quadrupole assemblies. The daughter ion selected by E is further subjected to low-energy collisional-activation dissociation (CAD) in q and the fragment-ion spectrum is obtained by scanning Q. The sequential daughter-ion-scanning technique has been used to establish that ‘internal’ fragments of the types, (AY′) and (BY′), are formed via initial Y-type cleavage. Fragmentation of a protonated peptide (angiotensin III) by loss of the C-terminal amino acid residue, yielding a (Bn′ + OH) ion, is reported for the first time. This process is analogous to that previously described for metal-cationized peptides.
    Additional Material: 8 Ill.
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  • 99
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 230-232 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Chemotaxonomic studies are frequently limited by the volume of data obtained and the difficulty of reducing this to statistically interpretable results. This paper describes the use of a straightforward procedure for relating the pattern of occurrence of sterols in fungi, analysed by mass spectrometry, to their classification.
    Additional Material: 4 Ill.
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  • 100
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    Rapid Communications in Mass Spectrometry 3 (1989), S. 238-240 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Pyrolysis-desorption/chemical-ionisation mass spectrometry (PyD/CIMS), using ammonia as ionization gas, was employed to investigate the influence of potassium hydroxide on the pyrolytic behaviour of glucans. The mass spectrum of native amylose, a 1 → 4 linked α-D-glucan, revealed an ion series pointing to desorption of intact 1,6-anhydro-oligosaccharides. Ions indicating oligomers up to the nonamer were observed. Addition of trace amounts of potassium hydroxide to amylose resulted in reduction in the size of the 1,6-anhydro-oligosaccharide ions and a simultaneous increase of ions resulting from ring rearrangements. Larger amounts of potassium hydroxide led to a complete loss of mass spectral information at the oligomer level.Similar mass spectrometric distributions in the PyD/CIMS data of a potassium hydroxide extracted tobacco fraction clearly reveal that alkali remnants must be present in this sample, which severly reduce the mass spectrometric information from polysaccharide oligomers. It is important to evaluate the role of inorganics on the thermal activation and subsequent fragmentation of biopolymers in PyD/CIMS experiments.
    Additional Material: 3 Ill.
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