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  • 1980-1984  (2,252)
  • Biochemistry and Biotechnology  (1,710)
  • Ultrastructure  (541)
  • Nuclear reactions
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 169 (1984), S. 1-8 
    ISSN: 1432-0568
    Keywords: Serotonin ; Primary visual cortex ; Monkey ; Ultrastructure ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A quantitative and immunoelectronmicroscopical analysis of serotonin nerve fibers in the primary visual cortex of the monkey (Macaca fuscata) was made using a sensitive immunoperoxidase method for serotonin. The overall numerical density of serotonin-containing varicosities in the primate striate cortex was approximately 770,000/mm3 and the highest concentration of immunore-active varicosities (ca. 1,400,000/mm3) was observed in the upper portion of layer IVc, the next highest concentration being in layer IVb (ca. 1,180,000/mm3). At the ultrastructural level, the electron dense immunoreactive products were observed in the small granules (10–65 nm in diameter). The varicosities were usually small (0.5–1.0 μm in diameter) and made contact with both stellate and pyramidal cells. Serotonin fibers were often in close apposition to the poorly myelinated axons in layers IVb, V, and VI, and they rarely formed distinct synaptic structures with unlabelled neuronal elements.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 169 (1984), S. 205-208 
    ISSN: 1432-0568
    Keywords: Rat uterus ; Epithelium ; Aging ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary By scanning electron microscopy uterine luminal epithelium of the rat was studied to determine whether aging alters ovarian hormone stimulated ultrastructural changes in that portion of the endometrial surface into which implantation takes place in the younger animal. Results show that in the aged rat this surface differentiates in response to ovarian hormones in a manner qualitatively similar to that which occurs in the young animal. Epithelial cells of ovariectomized rats, both young and aged, were polygonal in outline, flattened, or even somewhat concave, and had short microvilli. Following estrogen treatment cells of both groups were round or oval and bulged into the lumen. Cells of young rats were covered with long microvilli. Most cells of aged rats had microvilli of equal or greater length; a small number of epithelial cells had fewer and shorter microvilli. Cells of progesterone-treated young and aged animals both were covered with short microvilli and bore membrane protrusions. The protrusions varied in size, shape and numbers both within and between age groups. These findings suggest that differences in the surface ultrastructure of the aged uterus reflect age-related changes in hormone levels.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 170 (1984), S. 107-112 
    ISSN: 1432-0568
    Keywords: Ultrastructure ; Cumulus ; Oocyte complex ; Human egg
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cumulus cell mass enclosing a penetrated human egg was studied. The egg, recovered from the Fallopian tube approximately 80 h after luteinizing hormone peak and 35 h after insemination, was surrounded by a large, expanded and dissociated cumulus. Dispersions of the outermost cumulus cell layers occurred during processing, the innermost cell layers remained attached enclosing the egg. The photomicrographs showed that the follicular cells were embedded in an intercellular matrix and contact via gap-junction-like structures between neighboring cells existed. Cumulus cell processes traversing the zona pellucida were not found. Two types of follicular cells coexisted within the cumulus, light and dark cells. These cellular types, were different in morphology and size. Light cells displayed cytoplasmic organelles normally associated with protein synthesis and steroidogenesis. Dark cells with long cytoplasmic processes were involved in sperm phagocytosis. It is suggested from the characteristics of the cytoplasmic organclles that dark cells seem to be modified light follicular cells.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0568
    Keywords: Monoamine ; X-ray microanalysis ; Ultrastructure ; Brain stem ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary X-ray microanalysis after aldehyde-chromatedichromate treatment served to confirm the presence of monoaminergic terminals in the nucleus tegmentalis dorsalis (NTD) of the chicken. The monoaminergic terminals were represented as neuronal elements with electron-dense vesicles (EDVs) of several different shapes as seen in Eponembedded semi-thin sections. Conventional electron microscopic observations of the adjacent ultra-thin sections showed the EDVs to be comprised of spherical medium-sized (about 80 nm in diameter), large dense-cored (about 120 nm) and elongated granular vesicles (100–220 nm) in the same nerve varicosities. It is probable that the NTD, being a center of catecholaminergic efferent projections, may also receive direct monoaminergic inputs from an unknown area of the brain and/or from recurrent collaterals of the same catecholamine-containing neurons in the NTD.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 63 (1984), S. 269-275 
    ISSN: 1432-0533
    Keywords: Neurofibromatosis ; Cell culture ; Cell surface ; Cytoskeleton ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Structural proteins of cultured neurofibromatosis (NF) tumor and skin cells were studied with reference to control skin fibroblasts. In polyacrylamide gel electrophoresis (PAGE)/fluorography the banding patterns of the cell lysates were markedly similar. NF tumor cells, however, produced a 60 kD band with a stronger and a 48 kD band with a lighter protein staining and metabolic labeling intensity. Furthermore, skin cells were also characterized by a 26 kD protein and the tumor cells by a 22 kD protein with high metabolic labeling intensity. Neuraminidase/galactose oxidase/NaB3H4-labeled NF skin and control skin cells possessed a 220 kD protein that was less intensively labeled in the tumor cells. The banding pattern of the skin cells was also characterized by a protein with slightly lower molecular weight (86 kD) than that of the tumor cell lysates (90 kD). In all cell lines studied indirect immunofluorescence stainings revealed bright arrays of vimentin type intermediary filaments but no desmin, cytokeratin, glial fibrillary acidic protein (GFAP), or neurofilament proteins. NF skin and control skin cells possessed well developed actin-containing bundles of microfilaments, while those of the tumor cells lacked a typical stress-fiber organization. The general morphology of the tumor cell cultures was also irregular. Transmission electron microscopy revealed no basic differences in the structure of intermediary filaments or microfilaments. The present data provide basic knowledge of neurofibromatosis skin and tumor cells and demonstrate that cultured cells originating from neurofibromas are defective in both their intracellular and extracellular organization.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 65 (1984), S. 41-45 
    ISSN: 1432-0533
    Keywords: Colloid cyst ; Third ventricle ; Ultrastructure ; Pathogenesis ; Rathke's cyst
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The case involves a colloid cyst of the third ventricle in a 20-year-old man. The lining epithelia of the cyst were composed of two different types of epithelial cells; stratified squamous cells and mucincontaining columnar cells. The presence of both squamous and glandular cells in the cyst wall supports the contention that the colloid cyst in the present case derived from an non-neuroepithelial source. The clinico-pathology of this cystic tumor is compared here with other epithelial cysts of the central nervous system (CNS), especially Rathke's cyst.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 64 (1984), S. 81-84 
    ISSN: 1432-0533
    Keywords: Ganglioneuroma ; Cytoplasmic tubular inclusion ; Smooth endoplasmic reticulum ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Unusual tubular inclusions were observed in the cytoplasm of ganglion cells of a mediastinal ganglioneuroma in a boy of 7 years. The inclusions consisted of an aggregation of about 100-nm-sized tubular structures resembling ‘honeycomb-like’ tubular structures in the axoplasm of rats and mice and suggested to be derived from dilated rough endoplasmic reticulum. These structures differ from profiles reported in normal and pathologic conditions and seem to be related to the neoplastic character of the ganglion cells.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 64 (1984), S. 308-318 
    ISSN: 1432-0533
    Keywords: Angiogenesis ; Cerebellar hemangioblastoma ; Degranulation ; Heparin ; Mast cell ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The topographic distribution, population density, and ultrastructural features of mast cells were studied in six cases of cerebellar capillary hemangioblastoma. The vascular area of tumor tissue contained large numbers of mast cells (6.3 cells/high power field, ×400) in comparison with hyalinized area (0.3 cell) and adjacent cerebellar tissue (〈0.1 cell). Close association of mast cells with endothelial cells and stromal cells was found. The morphology of mast cell granules and their degranulation through dissolution of granule contents and exocytosis were illustrated. The findings suggest that an increased number of mast cells may represent one of the characteristic histological features of capillary hemangioblastoma, and continuous degranulation of mast cell granules with release of heparin may play an important pathophysiologic role in the vascular proliferation and expansion of the tumor.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 64 (1984), S. 282-296 
    ISSN: 1432-0533
    Keywords: Blood-nerve Barrier ; Perineurial barrier ; Leprosy neuropathy ; Ultrastructure ; Ferritin ; Ageing ; Drug treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Onset and nature of ultrastructural changes in endoneurial vasa nervorum during the pathogenesis of leprosy neuropathy and possibly associated alterations in the “blood-nerve barrier” were investigated, together with perineurial barrier functioning, in mice infected 20–28 months previously withMycobacterium leprae and in (ageing) non-infected mice. Barriers were tested by i.v. administration of markers (Trypan blue and ferritin) 1–4 days before killing the mice. Twenty-eight months after infection, histopathology of sciatic nerves was comparable to that seen in sensory nerves in clinically early human (borderline-) lepromatous leprosy. Schwann cells and endoneurial macrophages were bacillated, endothelia of endoneurial vessels not, and the perineurium rarely. Many infected mice and all (ageing) controls possessed ultrastructurally and functionally normal endoneurial vessels. Their continuous endothelium with close junctions had prevented marker passage, even when surrounding endoneurial tissue cells were quite heavily bacillated. The perineurium was also normal. By contrast, in infected mice showing hind limb paralysis serious histopathologic involvement and large globi of bacilli intrafascicularly in sciatic nerves, endoneurial blood vessels were abnormal. Open endothelial junctions, extreme attenuation, fenestrations, and luminal protrusions were all features comparable to neural microangiopathy encountered in leprosy patients (Boddingius 1977a, b). The “blood-nerve barrier” clearly had become defective allowing excessive exudation of Trypan blue and ferritin, via four pathways from the vessel lumen, deep into surrounding endoneurial tissues but halted by a normal perineurial barrier. Markers in such “blue” nerves were not found in bacillated or non-bacillated Schwann cells, thus denying significant phagocytotic and lysosomal activities of Schwann cells at this stage of neuropathy. Possible implications of barrier performances for anti-leprosy drug treatment of patients are discussed.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 65 (1984), S. 163-165 
    ISSN: 1432-0533
    Keywords: Human pinealomas ; Ultrastructure ; Paired twisted filaments ; Paired helical filaments ; Cytoskeleton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Paired twisted filaments (PTF) forming helices are described in tumor cells of three human pine-alomas. Each filament was 8.11±1.55 nm wide. The maximal width of the helix was 16.62±2.62 nm. The periodicity of the constrictions was 26.63±4.49 nm. These characteristics appeared original, suggesting protein, filaments possibly specific of pinealocytes. The similarities and discrepancies between PTF and Alzheimer's paired helical filaments (PHF) are discussed.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 62 (1984), S. 225-229 
    ISSN: 1432-0533
    Keywords: Dandy-Walker syndrome ; Dandy-Walker cyst ; Ependymal cell ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of the wall of the Dandy-Walker cyst has been described rarely. A boy aged 2 years was confirmed clinically, neuroradiologically, and operatively as having a Dandy-Walker cyst in the posterior fossa. The cyst wall obtained during surgery consisted of an outer arachnoid cell layer, intermediate interwoven neuroglial strands, and an inner layer of cells which lacked the characteristic appearance of ependyma. An unusual finding was a small, buried island of ependymal cells in the intermediate layer of the neuroglial tissue. Ultrastructural study of the cyst wall provides a better understanding of the pathogenesis of the Dandy-Walker syndrome.
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  • 12
    ISSN: 1432-0533
    Keywords: Anti-acetylcholine receptor antibody ; Experimental autoimmune myasthenia gravis ; Monoclonal antibody ; Myasthenia gravis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To investigate pathogenic mechanisms in experimental autoimmune myasthenia gravis (EAMG) and myasthenia gravis (MG), we studied the acute and chronic effects in rats of injection of rat monoclonal antibodies (MCABs) directed against the acetylcholine receptor (AChR). Animals were severely weak 12 h after a single injection, at which time macrophages were found invading endplate regions of muscle and cholinesterase-stained regions were separted from the underlying muscle fibers. Ultrastructural studies showed findings identical to the acute phase of EAMG: degenerating postsynaptic membranes and invasion and phagocytosis of endplate regions by macrophages. Animals receiving sublethal doses of MCAB recovered clinically by 4–5 days after injection. Recovery was accompanied by a progressive decrease in the number of macrophages associated with endplates and reapposition to the myofibers of the cholinesterasestained regions. Animals injected once, or repeatedly over several months, remained clinically and electromyographically normal after recovery from the initial episode of weakness, but their endplate ultrastructure was highly simplified with blunted or absent synaptic folds and shallow or absent secondary synaptic clefts. These studies demonstrate that anti-AChR MCABs can induce the changes of both acute and chronic EAMG. There is good correlation between the inflammatory changes and the acute clinical disease but poor correlation between morphological and clinical parameters in the chronic syndrome. The latter observation suggests that severe ultrastructural changes, similar to those seen in chronic EAMG and MG, cannot account, at least in rats, for the clinical and electrophysiologic abnormalities of MG.
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  • 13
    ISSN: 1432-0738
    Keywords: Trialkylphosphorothioates ; Rat ; Lung ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The oral administration of an LD50 dose (25 mg/kg) of O,S,S-trimethyl phosphorodithioate to rats induced immediate, cholinergic symptoms. A delayed respiratory crisis followed, 3–4 days later, involving a pronounced increase in lung weight and extensive injury to the alveolar epithelium. This compound also induced the immediate liberation of secretory granules from the Clara cells. Minor changes in the surface appearance of these cells were also observed but no signs of injury were found in any cells of the bronchiolar epithelium. The complement of secretory granules was monitored, by the morphometric analysis of ultrathin sections. Clara cells from control animals were found to contain 9.55±1.16 (SEM) granules per cell profile. The Clara cells from dosed animals were largely devoid of granules until the 3rd day after administration. Many of these agranular cells were arranged in clusters and often showed signs of mitotic division. In surviving animals the subsequent replacement of granules resulted in a large increase in the numbers present and many exhibited abnormal morphology. Over twice the normal complement of granules, 22.45±0.42 (SEM) per cell profile, was found 6 days after dosing. The complement of granules subsequently returned to normal levels and the clusters of Clara cells were resolved within 14 days of dosing.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 276 (1984), S. 170-177 
    ISSN: 1432-069X
    Keywords: Penile apocrine cystadenoma ; Ultrastructure ; Filamentous fuzzy coat ; Epidermoid metaplasia ; Peridermlike cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two cystadenomas occurring near the frenulum of the penis revealed a predominantly secretory pseudostratified columnar epithelium with PAS-reactive dome-shaped cytoplasmic protrusions at the luminal cellular parts. The content of secretory vacuoles was discharged into the cyst lumen by an exocytotic (eccrine) and ballooning type of extrusion. There were no indications of a real apocrine extrusion mechanism. No histogenetic derivation of these penile cystadenomas from apocrine sweat glands could be proved. An antennalike filamentous fuzzy coat on the luminal cytoplasmic membrane was most remarkable. Regionally, an epidermoid differentiation had developed. Morphologically, this process had begun just above the basal cell layer which had remained unchanged and led to the establishment of a stratified epithelium.Hyalin lamellarlike flattened cells at the luminal part displayed necrobiotic features and resembled periderm cells. There was no keratin pattern. Luminal cells of epidermoid differentiation still revealed a filamentous fuzzy coat which indicated that the undifferentiated cuboidal basal cells basically had a prospective secretory meaning and probably represented the target cells in the process of metaplasia.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 36 (1984), S. 550-555 
    ISSN: 1432-0827
    Keywords: Enamel crystals ; Length ; Shape ; Apatite ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary An original method for fractionating and preparing isolated crystals of homogeneous size was developed. It was demonstrated that enamel apatite crystals are at least 100 µm long. The flexibility of the very long crystallites was demonstrated. Crystal curvatures, accounting for the irregular course of the prisms through the enamel thickness, were visualized and measured. It was shown that in the deep forming enamel layer, lateral branches may grow out of the crystals and crystal fusing often occurs, inducing the crystallites to assume pyramidal shapes with their wide bases pointing toward the dentino-enamel junction and one or two tops toward Tomes' processes. During the maturation process, the two tops of the still immature crystals also fuse so that the mature crystals acquire a rodlike aspect, with parallel faces and steplike graduations along thec axis, allowing a close contact between the crystals. These results support the hypothesis that the crystallites would be continuous from the dentino-enamel junction to the surface.
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  • 16
    ISSN: 1432-072X
    Keywords: Methanogenium tatii ; Ultrastructure ; Physiology ; Glycoproteins ; DNA-DNA Homology ; Taxonomy ; Archaebacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new coccoid methanogen, Methanogenium tatii, was isolated and characterized. The mesophilic isolate can grow on and produce methane from H2:CO2 and formate. For growth acetate is strictly required. The cell shape, the G+C content of 54 mol% and DNA-DNA homology data suggest it to be a Methanogenium species.
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  • 17
    ISSN: 1432-072X
    Keywords: Nitrobacter hamburgensis ; Nitrite oxidoreductase ; Nitrate reductase ; Molybdenum iron-sulfur protein ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrite oxidoreductase, the essential enzyme complex of nitrite oxidizing membranes, was isolated from cells of the nitrifying bacterium Nitrobacter hamburgensis. The enzyme system was solubilized and purified in the presence of 0.25% sodium deoxycholate. Nitrite oxidoreductase oxidized nitrite to nitrate in the presence of ferricyanide. The pH optimum was 8.0, and the apparent K m value for nitrite amounted to 3.6 mM. With reduced methyl-and benzylviologen nitrite oxidoreductase exhibited nitrate reductase activity with an apparent K m value of 0.9 mM for nitrate. NADH was also a suitable electron donor for nitrate reduction. The pH optimum was 7.0. Treatment with SDS resulted in the dissociation into 3 subunits of 116,000, 65,000 and 32,000. The enzyme complex contained iron, molydbenum, sulfur and copper. A c-type cytochrome was present. Isolated nitrite oxidoreductase is a particle of 95±30 Å in diameter.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 138 (1984), S. 229-232 
    ISSN: 1432-072X
    Keywords: Actinomycetes ; Streptomyces torulosus ; Morphology ; Ultrastructure ; Verrucate spores ; Knobby ornamentation ; Sheath
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The type strain of Streptomyces torulosus Lyons and Pridham (1971) was studied by scanning- and transmission electron microscope. Spore chains were formed in spirals by aerial mycelium. The spores were connected by nozzles in which small channels could be observed. The knobby ornamentations of the spores arised on a thin fibrous sheath, enveloping the spore chains. These irregular blunt projections, called knobs, had varying diameters of 100 to 250 nm. The base of the knob, consisting of globose to flattened electron dense material, was sitting directly on the sheath. It was covered by several small vesicles of the same material. Each hollow vesicle beared a thin bowlshaped shell of electron transparent material. In general, the cupular bowls and their supporting vesicles became easily depressed on their base, but not detached from the surface of the spores. This type of knobby spore ornamentation was suggested to be designated as a verrucate spore type.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 57 (1984), S. 22-32 
    ISSN: 1432-1106
    Keywords: Ultrastructure ; Synaptology ; Hypoglossal nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of this study was to define the types and distribution of synaptic terminals in the hypoglossal nucleus (XII) of the rat. Based on differences in bouton and vesicle size and shape, synaptic specializations and association with postsynaptic organelles, five types of terminals were identified in XII. In order of decreasing frequency they were: 1) S-boutons (spherical vesicles with an asymmetrical synapse); 2) F-boutons (flattened vesicles with a symmetrical synapse); 3) P-boutons (pleomorphic admixture of flattened and spherical vesicles with a symmetrical synapse); 4) C-boutons (pleomorphic vesicles with a subsynaptic cistern); and 5) Tboutons (spherical vesicles with an asymmetrical synapse and subsynaptic dense bodies). S-boutons were the predominant type found on dendrites, while boutons containing flattened vesicles were more prevalent on motoneuron somata. C-boutons were restricted exclusively to cell bodies and large dendrites, and T-boutons were seen primarily on smaller dendritic profiles. These results are, in general, comparable to those previously described in the ventral horn and cranial nerve motor nuclei in several species. However, differences were noted. Specifically, large M-boutons and axo-axonic synapses were not observed in the present study. The functional significance of these findings are discussed in relation to oro-lingual behaviour.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 54 (1984), S. 385-389 
    ISSN: 1432-1106
    Keywords: Synaptosome ; 4-Aminopyridine ; Ultrastructure ; Exocytosis ; Recycling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pinched-off nerve terminals (synaptosomes) from rat cerebral cortex were depolarized with 60 mM KCl and treated with 20 mM 4-aminopyridine in order to evaluate ultrastructural alterations. The empty presynaptic terminals were counted and their number was given as a percentage of the normal terminals. The proportion of empty terminals increased from 10.47±1.56% to 32.45±1.88% (P 〈 0.001) following treatment with 20 mM 4-aminopyridine. This effect of 4-aminopyridine depended on the presence of Ca++ in the incubation medium. The results are discussed in terms of facilitation by 4-aminopyridine of exocytotic transmitter release. We think that the increase of the empty synaptosomes was due to the exhaustion or inhibition of the synaptic vesicle recycling mechanism.
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  • 21
    ISSN: 1432-2307
    Keywords: Acromegaly ; hyperprolactinemia ; McCune-Albright syndrome ; pathology ; Pituitary ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An 11-year-old girl, with the McCune-Albright syndrome, exhibited fibrous dysplasia of several bones, skin pigmentation, precocious puberty, growth hormone hypersecretion, acromegaly and hyperprolactinemia. Histologic, immunocytologic and ultrastructural investigation of the surgically-removed pituitary showed massive mammosomatotroph hyperplasia. Since no adenoma was found, the abundance of these bihormonal cells, capable of producing both growth hormone and prolactin, was implicated in the causation of growth hormone and prolactin excess. Somatoliberin overproduction and/or somatostatin and dopamine deficiency could not account for the hypophysial abnormality, since changes in secretory rates of these hypothalamic hormones would lead to proliferation of mature somatotrophs and lactotrophs, rather than mammosomatotrophs. In our patient, a congenital hypothalamic malfunction might have been accompanied by hypersecretion of an unidentified releasing factor, resulting in pathologic differentiation of the pituitary and mammosomatotroph hyperplasia. Alternatively, mammosomatotroph hyperplasia may have been due to an inherent genetic or embryonic defect affecting primarily the pituitary. According to this interpretation, the pituitary lesion represented yet another developmental error in the setting of the McCune-Albright syndrome.
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  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 404 (1984), S. 177-185 
    ISSN: 1432-2307
    Keywords: Oesophagitis ; Herpetic cell change ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ultra-thin sections obtained from routine biopsy specimens and cytological smears of 3 cases, together with one autopsy case suggestive of herpes oesophagitis, clearly demonstrate herpes viruses. The infected epithelial cells reveal different stages of virus replication and propagation. Cowdry A type inclusion bodies, however, representing early alterations in the course of infection are less frequent. Ground-glass looking nuclei of light microscopical balloon cells and infected multinuclear giant cells of epithelial origin are characteristic changes of the late ulcerative stage of herpes oesophagitis usually seen at the time of detection. These typical virus induced cell changes are mostly to be found at the ulcers edge.
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  • 23
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 404 (1984), S. 253-263 
    ISSN: 1432-2307
    Keywords: Ameloblastic fibrosarcoma ; Histogenesis ; Histopathology ; Ultrastructure ; Fatal case
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This report presents a fatal case of ameloblastic fibrosarcoma arising from an ameloblastic fibroma, originating in the maxilla of 19-year-old Japanese male. An analysis of previously reported fatal cases of ameloblastic fibrosarcoma is included. In the course of the disease, the mesenchymal component of ameloblastic fibroma showed a dramatic histopathological transformation into sarcoma following multiple recurrence and the patient died of uncontrollable local infiltration of the cranial base. Although many cases have seemed to show disappearance of the epithelial component as malignant transformation progressed, many benign appearing ameloblastoid epithelial masses were scattered throughout the sarcomatous area even in the fatal stage in the present case. No distant metastases were found at autopsy. During multiple recurrences of the lesion, a little dysplastic dentin which was closely associated with both epithelial and mesenchymal components was found, though it could not be observed in autopsy material. Ultrastructural findings in autopsy material showed that the mesenchymal component consisted of undifferentiated mesenchymal cells, fibroblastic and fibrocytic cells with marked cellular and nuclear pleomorphism and that the epithelial component closely resembled the enamel organ.
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  • 24
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 403 (1984), S. 361-376 
    ISSN: 1432-2307
    Keywords: Neurofibrosarcomas ; Neurogenic sarcomas ; Von Recklinghausen's disease ; Malignant schwannomas ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Thirteen soft tissue neurogenic sarcomas from twelve patients with neurofibromatosis (Von Recklinghausen's disease) were ultrastructurally examined. Electron microscopic studies revealed a wide spectrum of morphological manifestations varying from schwannian to fibroblastic, histiocytic, fibrohistiocytic and relatively undifferentiated cellular proliferations. A similar variation on light microscopic appearances has been previously reported in these neurogenic sarcomas. Neurogenic sarcomas occurring in patients with neurofibromatosis (Von Recklinghausen's disease), represent a heterogenous group of neoplasms with various patterns of differentiation identified ultrastructurally. The morphologic expressions of these neurogenic neoplasms can be conceptualized as a disorderly growth of the various peripheral nerve cellular components, or, as has been previously suggested, as a result of the multipotential nature and metaplastic ability of Schwann cells. S-100 protein immunohistochemistry was only positive in those neoplasms ultrastructurally proven to represent schwannian cellular proliferations. This study serves to document the range of fine structure that may be found in neurogenic sarcomas, to correlate the ultrastructural findings with the light microscopic appearance of these tumors, to determine the specificity of the electron microscopic findings, and immunohistochemistry for S-100 protein and assess their possible value in differential diagnosis.
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  • 25
    ISSN: 1432-2307
    Keywords: Localized fibrous tumour of the pleura ; Benign mesothelioma ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Five localized fibrous tumours of the pleura (benign mesothelioma) were studied ultrastructurally in order to elucidate their histogenesis. The histological subtypes of this benign fibrous lesion of the visceral pleura, i.e. the cellular, the collagenous, and the hyaline, were separately analysed. The tumours are composed of undifferentiated mesenchymal cells, intermediate and differentiated fibroblasts as well as collagenous interstitial tissue. The varying distribution of these cell elements account for the various histological subtypes. Morphological similarities between the mesenchymal tumour cells and the superficial mesothelial cells, which are always separated from the true tumour tissue by an intact basement membrane, were not observed. The different cellular elements can be regarded as parts of a continuous spectrum of cytodifferentiation, in which the mature fibroblasts are derived via intermediate forms from the undifferentiated cells. It is concluded that the localized fibrous tumours of the pleura arise from immature mesenchymal stem cells, which seems to be normally found in the submesothelial layer of the visceral pleura.
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  • 26
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    European archives of oto-rhino-laryngology and head & neck 239 (1984), S. 49-59 
    ISSN: 1434-4726
    Keywords: Glycerol ; Inner ear ; Ultrastructure ; Cellular and paracellular transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect has been studied of intravenously administered glycerol on paracellular and cellular transport of macromolecular HRP tracer in the lateral cochlear wall. The findings indicate osmotically induced diffusion phenomena by the opening of shunt pathways through junctional complexes in the stria vascularis. Vesicular transport is accelerated, direction of transport however is not affected by the changed osmolality.
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  • 27
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    Diabetologia 27 (1984), S. 397-402 
    ISSN: 1432-0428
    Keywords: Ultrastructure ; heart muscle ; streptozotocin ; short-term diabetes ; insulin treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of myocardium was examined in short-term diabetic rats. Morphometric analysis showed the volume of myocytic mitochondria, sarcoplasmic reticulum and lipid droplets to be significantly increased compared with those of control animals. Further measurements of mitochondria and sarcoplasmic reticulum indicated that the augmentation of these compartments was accountable by the enlargement of pre-existing mitochondria, which were swollen, and of pre-existing tubules of sarcoplasmic reticulum, the lumen of which was dilated. After insulin treatment the morphological changes were returned to normal which indicates that they were not due to the toxic effect of streptozotocin but were caused by the diabetic state per se. This suggestion is further supported by the finding that experimentally induced metabolic acidosis without diabetes did not cause any morphologically detectable changes in the heart muscle. It is concluded that short-term diabetes in the rat causes mitochondrial swelling, dilatation of sarcoplasmic reticulum and accumulation of lipid in cardiac myocytes, and that these changes are preventable with insulin treatment. We suggest that insulin may have an important role in the maintenance of metabolism in heart muscle.
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  • 28
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    Virchows Archiv 402 (1984), S. 331-336 
    ISSN: 1432-2307
    Keywords: Carcinoid ; Uterine cervix ; Histopathology ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of carcinoid tumor of the uterine cervix is reported. The patient was a 76-year-old Japanese woman with a complaint of vaginal bleeding. She was clinically diagnosed as stage IVb carcinoma of the uterine cervix. Light microscopically, the tumor was characterized by formation of solid cell nests and, in limited areas, glandular structures. The tumor cells in solid cells nests showed positive argyrophil reaction but were negative for argentaffin reaction. At the ultrastructural level, the cytoplasm of the tumor cells contain numerous neurosecretory granules, microfilaments and well-developed Golgi complexes. On the bases of histochemical and electron microscopic features of tumor cells, the tumor was diagnosed as carcinoid tumor of the uterine cervix.
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  • 29
    ISSN: 1432-2307
    Keywords: Mesothelioma ; Histogenesis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary During an ultrastructural review of 30 diffuse and 10 localized mesotheliomas, it was apparent that some micrographs showed various stages in the developmental processes involved in the formation of histological patterns in diffuse mesotheliomas and a histogenetic link between diffuse and localized mesotheliomas. Cells in the stromal or sarcomatous regions of diffuse mesothelioma often show varying degrees of mesothelial differentiation and a gradual transition to cells with typical mesothelial characteristics that organize into structures recapitulating the surface layer of serosal membranes. Tumor cells in localized mesotheliomas had many similarities to the “stromal” cells in the diffuse counterpart including intercellular junctions, rare microvilli and occasional foci of basal lamina. It is postulated that diffuse and localized mesotheliomas share a common histogenetic origin as a result of neoplastic induction of specialized submesothelial cells. In this concept, tumor cells in diffuse mesotheliomas reflect stages in the differentiation and organization of normal serosal membranes and localized mesotheliomas mirror the earliest phases of this process.
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  • 30
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    Virchows Archiv 402 (1984), S. 439-450 
    ISSN: 1432-2307
    Keywords: Atypical germ cells ; Carcinoma in situ of the testis ; Normal germ cells ; Ultrastructure ; Differential diagnosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It is uncertain whether the so called intratubular atypical germ cells (carcinoma in situ cells) demonstrable in the testicular tissue around different germ cell tumors and in testicular biopsies of patients with impaired fertility are identical with regard to their morphology and further development. Thus atypical germ cells of 18 patients with testicular germ cell tumors and of 3 patients with atypical germ cells in testicular biopsies without tumor were studied by electron microscopy and/or by immunohistochemistry. The atypical germ cells show characteristic alterations distinguishing them from normal germ cells, especially spermatogonia. However, there are no differences between atypical germ cells in the above mentioned groups. Immunohistochemical reactions are negative with anti-alpha-fetoprotein and anti-beta-human-chorionic-gonadotropin, but 6 of the 15 cases are positive with antiferritin. However, this positive reaction occurs in cases in different diagnostic groups. Atypical germ cells of the different groups cannot be distinguished by electron microscopy or immunohistochemical methods, but further investigations vestigations, including cell cultures, may provide more information.
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  • 31
    ISSN: 1432-2307
    Keywords: Proximal tubule ; Atrophy ; Cortical interstitium ; Human nephropathy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A systematic ultrastructural analysis of proximal tubule atrophy and cortical interstitial changes was carried out in human chronic nephropathy. The investigation was based on human hydronephrotic kidneys, which had been surgically removed and subsequently perfusion-fixed for light and electron microscopy. Normal kidney tissue, which was derived from nephrectomy specimens with pathological changes confined to part of the kidney or to the renal pelvis, was used for control material. A slight degree of proximal tubule atrophy was characterized by reduction of mitochondria and basolateral membranes, enlargement of large endocytic vacuoles and increased numbers of lysosomes containing lamellar material. In moderate atrophy these changes were further accentuated, and in addition there was an increasing loss of microvilli and a reduction of endocytic invaginations and small endocytic vacuoles. In severe atrophy all types of organelles were sparse and the architecture of the tubule cells greatly simplified. A distinctive feature of atrophic tubules was the presence in the tubule cells of large bundles of actin-like filaments, which were often associated with outpouchings of basal cell parts and basement membrane. The reduction of mitochondria and basolateral cell membranes and the changes of endocytic vacuoles and lysosomes indicate that proximal tubule atrophy also in early stages may be associated with impairment of tubular transport processes. Comparisons with previous observations in various types of experimentally induced tubule cell degeneration and with the ultrastructure of regenerating proximal tubule cells provide some evidence that degenerative changes as well as imperfect regeneration of tubule cells may contribute to the alterations of ultrastructure in tubular atrophy. It is suggested that changes of the cortical interstitium may be of pathogenic importance for the progression of tubular atrophy by altering the spatial relationships between tubules and capillaries.
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  • 32
    ISSN: 1432-234X
    Keywords: Ultrastructure ; Gills ; Epithelial cells ; Polychaeta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of gill epidermal cells of Diopatra neapolitana and their relationship with blood spaces are described. The existence of a basal infolding complex, related to the blood spaces, is also reported. A possible involvement of these cells in osmoregulation and ion interchange, apart from their well-known role in respiration, is suggested.
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  • 33
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    Journal of cancer research and clinical oncology 107 (1984), S. 183-194 
    ISSN: 1432-1335
    Keywords: Collagen ; Stereology ; Oral carcinogenesis ; Inflammation ; Ultrastructure ; Lamina propria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Stereological point-counting methods were used to determine the volumetric alterations in collagen from the lamina propria immediately beneath the epithelial-connective tissue junction in hamster check-pouch mucosa treated with the chemical carcinogen DMBA. In addition, a non-neoplastic inflammatory control was evaluated in which a delayed hypersensitivity reaction was induced by the contact-sensitising agent DNCB. DMBA-treated tissues were assigned to histopathologically defined hyperplasia, dysplasia and carcinoma stages. The volume densities of collagen present in unit volume of extracellular lamina propria were found to decrease progressively and significantly in DMBA-treated tissues when compared with values obtained from normal untreated mucosa. Values from the inflammatory control were comparable with those from the dysplasia stage of carcinogenesis. The mechanisms responsible for these decreases in collagen volume density are unknown, but contributory factors might include collagen destruction by enzymes originating in either the epithelium or the cells of the inflammatory infiltrate, dilution of collagen produced by inflammatory oedema or alterations in the synthetic capabilities of fibroblasts.
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  • 34
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    Theoretical and applied genetics 68 (1984), S. 305-309 
    ISSN: 1432-2242
    Keywords: Impatiens ; Microspore mitosis ; Plastid distribution ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This paper describes the unequal distribution of plastids in the developing microspores of Impatiens walleriana and Impatiens glandulifera which leads to the exclusion of plastids from the generative cell. During the development from young microspore to the onset of mitosis a change in the organization of the cytoplasm and distribution of organelles is gradually established. This includes the formation of vacuoles at the poles of the elongate-shaped microspores, the movement of the nucleus to a position near the microspore wall in the central part of the cell, and the accumulation of the plastids to a position near the wall at the opposite side of the cell. In Impatiens walleriana, the accumulated plastids are separated from each other by ER cisterns, and some mitochondria are also accumulated. In both Impatiens species, the portion of the microspore in which the generative cell will be formed is completely devoid of plastids at the time mitosis starts.
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  • 35
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    Virchows Archiv 404 (1984), S. 7-16 
    ISSN: 1432-2307
    Keywords: Fibroadenoma ; Stromal cells ; Actin ; Ultrastructure ; Myofibroblast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Fourteen fibroadenomas of the human breast were examined by light and electron microscopy, and by immunohistochemistry for actin. They were classified into 3 groups according to their stromal patterns; myxoid, fibrous-cellular and sclerotic. Actin immunohistochemistry revealed that the stromal areas were strongly positive in the fibrous-cellular group and weakly positive in the myxoid and sclerotic groups. By electron microscopy the stromal cells in most cases of the myxoid and fibrous-cellular groups were fibroblasts, containing varying amounts of microfilaments, 5–7 nm in diameter (actin type filaments). However, a dense body was not usually present suggesting these stromal cells were variants of myofibroblasts. The amount of microfilaments in fibroblasts was greater in the fibrous-cellular group than in the myxoid group. This was consistent with the results of actin immunohistochemistry. In 3 cases of the fibrous-cellular group peculiar structures simulating Z-lines of striated muscles were noted in some stromal cells. Since no myosin filaments were detected, they were regarded as intermediate structures between Z-lines of striated muscles and dense bodies of smooth muscles. In the sclerotic group, stromal fibroblasts were sparse and had fewer organelles.
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  • 36
    ISSN: 1432-2307
    Keywords: Morphometry ; Human bladder tumour ; Human chronic cystitis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Transmission (TEM) and scanning electron microscopic (SEM) observations were performed on well-differentiated tumours and chronic cystitis in the human urinary bladder. SEM showed that the pleomorphic microvilli were present not only on the luminal surface of the tumour but also on the surface of inflammatory mucosa. The ultrastructure of six tumours and 5 cases of chronic cystitis was evaluated morphometrically. Bladder tumour and inflammatory mucosa were divided into several layers, namely outermost cells (S), subsurface cells just beneath these (S1), subsurface cells of 2 or 3 layers below (S23), intermediate cells of 2 or 3 layers above the basal cells (123), intermediate cells just above the basal cells (I1) and basal cells (Ba). Areas of nucleus, cytoplasm and cytoplasmic organelles, numbers of nucleoli, nuclear bodies, mitochondria and lysosomes together with irregularity of the cell and nucleus were estimated according to the methods of Weibel. A multi-variate analysis of variance on these variables showed that the above subdivision of layers was necessary for the comparison of tumour and inflammation. Discriminant analysis showed various differences between tumour and inflammatory mucosa. The results indicated that the Ba layer is the most effective site for differentiating the tumour from inflammation. Ba cells with large and irregular cytoplasm with an enlarged Golgi area, accompanied by many vacuolar structures, may be indicative of tumour rather than inflammation.
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  • 37
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    Virchows Archiv 405 (1984), S. 41-53 
    ISSN: 1432-2307
    Keywords: Fibromatosis ; Dupuytren's contracture ; Myofibroblast ; Ultrastructure ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Forty three cases of palmar fibromatosis were studied by light and electron microscopy, enzyme histochemistry, and ultrastructural immunohistochemistry. By electron microscopy most of the cells composing the nodules in both the proliferative and the involutional stages were identical to myofibroblasts. The myofibroblasts in the involutional nodules often possessed microfilament aggregates probably representing contraction of micro(actin)fllaments in the cytoplasm. The proliferative nodules revealed small perivascular haemorrhages and haemosiderin deposits accompanied by accumulation of macrophages and some lymphocytes; these inflammatory cells possibly secrete a certain growth factor inducing proliferation of genetically abnormal fibroblasts and myofibroblasts. Diaminopeptidase IV was detected in myofibroblasts and fibroblasts by enzyme histochemistry and ultrastructural immunohistochemistry; the enzyme may play a role in the metabolism of intercellular substances. Some perivascular mesenchymal cells, interpreted as variants of myofibroblasts, had moderate activity of alkaline phosphatase.
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  • 38
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    Urological research 12 (1984), S. 187-192 
    ISSN: 1434-0879
    Keywords: Gossypol ; Bull spermatozoa ; Motility ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Gossypol acetic acid in a concentration of 1,000 μg/ml solvent is able to immobilize 1 ml of native bull semen (sperm concentration: 8.5×108/ml; motility rate: 87.4%) within 30 min. After GAA treatment the spermatozoa show severe morphological damage on the membrane system, on the acrosomal complex and on the tubular complex of the end piece. The working mechanism of GAA can be assumed to be inactivation of enzyme activities or in direct reactions with plasma membrane material.
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  • 39
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    European archives of oto-rhino-laryngology and head & neck 239 (1984), S. 133-144 
    ISSN: 1434-4726
    Keywords: Esthesioneuroblastoma ; Intermediate filaments ; Secretory granules ; Ultrastructure ; Immunohistology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of esthesioneuroblastoma, the pathological diagnosis of which almost always causes great difficulties, was investigated ultrastructurally, biochemically, and immunohistologically, using antibodies against the five known types of intermediate filaments [keratin, vimentin, desmin, glial fibrillary acidic protein (GFAP) and neurofilaments]. The tumour cells did not react with antibodies against any of the five intermediate filament proteins. Ultrastructural investigations showed dense cored secretory granules in the cytoplasm and cell processes. Thus, immunohistology offers by “exclusion” a differential diagnosis to avoid often misdiagnosed tumours (undifferentiated carcinomas, embryonal rhabdomyosarcomas, and malignant lymphomas), since carcinomas react with antikeratin, embryonal rhabdomyosarcomas with antibodies to desmin and malignant lymphomas show immunofluorescence with antibodies to vimentin. The biological behaviour (age distribution, tendency to metastasize), the normal values of biochemical parameters, homovanillic acid and vanilmandelic acid (HVA, VMA), and the absence of neurofilaments distinguish this type of tumour from the peripheral sympathetic neuroblastoma.
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  • 40
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    International orthopaedics 7 (1984), S. 215-221 
    ISSN: 1432-5195
    Keywords: Experimental arthrosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs ont réalisé une arthrose expérimentale chez le chien en injectant dans une articulation le liquide obtenu par ponction d'une autre articulation du même animal, dont le cartilage a été préalablement scarifié de façon aseptique. L'examen des surfaces articulaires en microscopie électronique montre des altérations dégénératives progressives au niveau de la matrice extra-cellulaire, des chondrocytes et de la membrane péri-cellulaire. Ces modifications augmentent après des injections répétées de liquide synovial. Dans une autre série d'animaux, on a injecté soit le culot de centrifugation, soit le surnageant et on a comparé les effets obtenus vis-à-vis des structures cellulaires et extra-cellulaires.
    Notes: Summary Experimental arthrosis was induced in previously healthy joints in a group of dogs by injection of fluid aspirated from another joint of the same animal previously damaged by trauma under sterile conditions. Using electron microscopy progressive degenerative changes were observed at the surface of the joint, in the extracellular matrix, in the chondrocytes and in the pericellular band. The changes increased following serial injections of the joint fluid. In another series, the joints were injected either with the centrifuged concentrate or the supernatant fluid and a comparison made of the contrasting effects upon the cellular and extracellular structures.
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  • 41
    ISSN: 1573-5036
    Keywords: Actinorhizae ; Datisca cannabina ; Frankia ; Nitrogen fixation ; Root nodules ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The fine structures of the microsymbiont inside the root nodules ofDatisca cannabina have been studied by light, by transmission- and by scanning-electron microscopy. The endophyte is prokaryotic and actinomycetal in nature. The hyphae are septate and branched, diameter 0.3–0.5 μm. The tips of hyphae are swollen to form electron-dense, clubshaped to filamentous vesicles, ranging in diameter: 0.4–1.4 μm. The endophyte penetrates through walls of the cortial cells. The infected zone is kidney shaped and confined to one side of the acentric stele. The orientation of infection is reversed from other actinorhizae exceptCoriaria. The hyphae are near the host cell wall and vesicles are directed towards the central vacuole. Vesicles are aseptate and no collapsing of the vesicle cell wall (void area) has been observed. Vesicle clusters structures are globular with an opening at one side of the cluster. The host cell is multinucleate or contains a lobed nucleus. Groups of mitochondria are located in between the hyphae, suggesting a strong association between the host and the endophyte for energy supply and amino acid production. The consequences of the inability to separate the mitochondria from the vesicle clusters in nodule homogenates in physiological studies have been discussed. Isolated vesicles clusters showed dehydrogenase activity, indicated by the presence of formazan crystals, after incubation with NADH and NBT. Strongest reducing activity was found within the vesicles. The possible role of filamentous vesicles in nitrogen fixation has been discussed.
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  • 42
    ISSN: 1573-5036
    Keywords: Aeration status ; Microorganisms ; Mucilage ; Rhizosphere ; Ultrastructure ; Wheat root
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Outer layers of wheat roots grown in aerated and unaerated nutrient solutions were studied by transmission electron microscopy. Root growth was considerably impaired in unaerated nutrient solution. In contrast to aerated roots, no mucilaginous layer but dense bacterial colonization were observed on the root caps of unaerated roots. The root cap mucilage had apparently been decomposed by the microorganisms. The peripheral root cap cells of the unaerated roots appeared to contain less cell organelles than those of the aerated roots, while the central cap cells and the meristematic cells of the root tip seemed not to be affected by lack of aeration. The bacterial population in the elongation, root hair, and lateral root zones, was also remarkably higher on roots grown in unaerated nutrient solution. In the lateral root zone of unaerated roots, even the cortical cells were invaded by bacteria.
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  • 43
    ISSN: 1573-5036
    Keywords: Alnus Hippophaë ; Mycorrhiza ; Myrica ; Nitrogenase ; Phosphate ; Triple symbiosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The roots ofHippophaë rhamnoides which regularly bear actinomycete induced nodules when growing on Scottish sand dunes have also been found to support an endomycorrhizal association withGlomus fasciculatus. Ultrastructural and cytochemical studies carried out on the indigenous infections of establishedHippophaë mycorrhizal roots would support the postulate that transport is indeed occurring between the fungal symbiont and the host plant and vice versa in respect of phosphate and carbohydrate. Experiments using various inoculation regimes, demonstrated the significant improvement in the mycorrhizal/nodulated plants compared to the nodulated-only and the mycorrhizal-only plants with respect to plant growth, uptake of phosphate and nitrogenase activity, when grown in a medium poor in combined nitrogen and soluble phosphate. Preliminary work onAlnus andMyrica species growing in Central Scotland indicates that the mycorrhizae associated with these nodulated root systems exhibit a different interaction pattern which may be dependent on habitat type and associated angiosperm species.
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  • 44
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 121-127 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A kinetic model was devised for the hydrolysis and synthesis of maltose and isomaltose by two glucoamylases from Rhizopus niveus and Aspergillus niger, and the validity of the model was verified experimentally at 313 K and pH 5.0. For both enzymes, the formations of maltose and isomaltose from glucose were parallel reversible reactions, and glucosyl transfer between maltose and isomaltose was not observed. The enzymes catalyzed rapid hydrolysis and synthesis of maltose. Isomaltose was hydrolyzed and synthesized more slowly, but the level produced from glucose was much higher than that of maltose. These hydrolysis and condensation reactions were expressed well by the model.
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  • 45
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 128-133 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pichia polymorpha has inulinase activity and could be used for the production of fructose syrup from inulin. The application of immobilized P. polymorpha whole cells for the continuous hydrolysis of inulin is, however, limited since the biosynthesis of this enzyme system is repressed by the reaction products, dextrose and fructose. A derepressed mutant hyperproducer of inulinase was isolated after treatment with EMS followed by a selection step with deoxyglucose.
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  • 46
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 134-141 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The technique of cell immobilization using porous support particles (biomass support particles) has been successfully applied to yeast cells. Two reactor configurations exploiting the use of these particles have been developed and assessed for use in aseptic yeast fermentations. A liquid-fluidized bed fermenter has been devised for use with particles denser than the fermentation liquor whilst a gas-stirred circulating bed fermenter proved suitable for particles of essentially neutral buoyancy. Both systems have been operated successfully for extended periods of continuous operation. The utilization of biomass support particle technology in such reactors provides a practical and robust system for immobilized cell reactors. This technology offers significant opportunities for further development.
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  • 47
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 142-147 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biomass autoflocculation in outdoor algal cultures was found to be associated with increases of culture pH levels, due to CO2 consumption by the algal photosynthetic activity. Under these alkaline conditions, some medium chemical ions precipitated together with the algal biomass. The chemical substances involved with the process and its dependence on pH value were studied by simulation of autoflocculation in laboratory experiments. Proper concentrations of calcium and orthophosphate ions in the medium are important for autoflocculation and, in order to attain it within the pH range 8.5-9.0, the culture should contain 0.1mM-0.2mM orthophosphate and 1.5mM-2.5mM calcium prior to raising the pH level. Calcium phosphate precipitates are considered as the flocculating agent which reacts with the negatively charged surface of the algae and promotes aggregation and flocculation.
    Additional Material: 7 Ill.
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  • 48
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 156-166 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental investigation is by far the most effective approach for studying the behavior of physical systems. However, an enzymatic solubilization of vegetable protein is a complex combination of intrinsic problems, of which many are not easily adaptable to experimental investigation. Experimental designs to study enzyme vegetable protein reactions yield data which describe the extramembraneous activity of the immobilized enzyme. In a continuous recycle immobilized enzyme reactor, the microenvironment concentration of the substrate or product in the membrane phase, or the concentrations along the reactor axial length in the bulk phase are not discernible to the experimenter. However, the knowledge of such concentration profiles is important in weighing the significance of such factors as intermembrane diffusion, enzyme loading, wet membrane size, and the mode of operation of the reactor. The simulation of mathematical models, which describe the physical system within the constraints imposed, yields information which is vital to the understanding of the process occurring in the reactor. The kinetics and diffusion of an immobilized thermophilic Penicillium duponti enzyme at pH 3.4-3.7 and 50°C was modeled mathematically. The kinetic parameters were evaluated by fitting a model to experimental data using nonlinear regression analysis. Simulation profiles of the effects of reactor geometry, substrate concentration, membrane thickness, and enzyme leading on the hydrolysis rate are presented. From the profiles generated by the mathematical model, the best operational reactor strategy is recommended.
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  • 49
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    Biotechnology and Bioengineering 26 (1984), S. 188-190 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Tab.
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  • 50
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    Biotechnology and Bioengineering 26 (1984), S. 257-264 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bioconversion of acetic acid to methane by a crude culture of methanogens in a continuous multireactor system was investigated. Culture of methanogens was drawn from an active cow-dung digester (12 days) and was grown in a semisynthetic medium (pH 6.3, 37°C) with acetic acid as the sole carbon source. The solubilities of CO2, HCO3-, and CO32- increased with the rise in pH and exercised considerable influence on the gas composition. Various mechanisms for methanogenesis of acetic acid based on the available pathways were considered. Experimental data were compared with these mechanisms, the best fit was determined, and the corresponding rate expression was identified. This mechanism predicted that, of the total methane produced, 72%;comes from acetic acid directly and 28%;via the CO2 reduction route.
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  • 51
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    Biotechnology and Bioengineering 26 (1984), S. 340-346 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The rate of celluose degradation, limited due to the inhibition by cellobiose, can be increased by the hydrolysis of cellobiose to glucose using immobilized β-glucosidase. Production of β-glucosidase in four yeasts was studied and a maximum activity of 1.22 IU/mg cells was obtained in cells of Pichia etchellsii when grown on 3% cellobiose as the sole carbon source. A study of the immobilization of β-glucosidase containing cells of Pichia etchellsii on various solid supports was conducted and immobilization by entrapment in calcium alginate gel beads was found to be the most simple and efficient method. A retention of 96.5% of initial activity after ten sequential batch uses of the immobilized preparation was observed. The pH and temperature optima for free and immobilized cells were the same, i.e., 6.5 (0.05M Maleate buffer) and 50°C, respectively. Even though the temperature optimum was found to be 50°C, the enzyme exhibits a better thermal stability at 45°C. Beads stored at 4°C for six months retain 80% of their activity. Kinetic studies performed on free and immobilized cells shown that glucose is a noncompetitive product inhibitor.The immobilized preparation was found to be limited by pore diffusion but exhibited no film-diffusion resistance during packed bed column indicated by a low dispersion number of 0.1348. A model for reaction with pore diffusion for a noncompetitive type of inhibited system was developed and applied to the cellobiose hydrolysis system. The rate of reaction with diffusional limitations was determined by using the model and effectiveness factors were calculated for different particle sizes. An effectiveness factor of 0.49 was obtained for a particle diameter of 2.5 mm. The modified rate expression using the effectiveness factor represented batch and packed bed reactor operation satisfactorily. The productivity in the packed bed column was found to fall rapidly with increase in conversion rate indicating that the operating conditions of the column would have to be a compromise between high conversion rates and reasonable productivity. A half-life of over seven days was obtained at the operating temperature of 45°C in continuous operation of the packed bed reactor. However, the half-life in the column was found to be greatly affected by temperature, increasing to over seventeen days at a temperature of 40°C and decreasing to less than two days at 50°C.
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  • 52
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    Biotechnology and Bioengineering 26 (1984), S. 347-351 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Invertase immobilized onto corn grits was utilized in the hydrolysis of highly concentrated sucrose solutions producting liquid sugar solutions containing glucose and fructose. Comparisons of conversion efficiencies of this immobilized invertase in a continuous stirredtank reactor and a plug-flow reactor indicated that the plug-flow reactor has an higher efficiency. Continuous sucrose hydrolysis was then performed in 0.1- and 1-L tubular reactors. This tenforld scaling-up was achieved without any noticeable loss in efficiency. This process thus was scaled-up to a 17.6-L pilot reactor set in a cane sugar refinery. This reactor was fed with highly concentrated sucrose solutions [71% (w/w)] to produce invert sugar syrup with the desired inversion degree. It allows a productivity equal to 9.1 kg sucrose hydrolyzed/h in the case of a 69% (w/w) sucrose initial concentration with a 72% conversion rate.
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  • 53
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    Biotechnology and Bioengineering 26 (1984), S. 352-361 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model has been developed which describes organics removal, oxygen utilization, ammonianitrogen removal, ortho-phosphate removal, and biomass production in an aggregated microbial suspension containing a uniform floc size and the organics as a soluble biodegradable material. It is applicable to both steady-state and transient conditions, as well as to systems experiencing only carbon oxidation or to systems experiencing both carbon oxidation and nitrification. The model, consisting of five partial differential equations and four ordinary differential equations, takes into account the flow pattern in the reactor, intraparticle mass transport of oxygen, organics, ammonia-nitrogen and ortho-phosphate, and biochemical reactions by the individual cells embedded in the floc.
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  • 54
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    Biotechnology and Bioengineering 26 (1984), S. 390-391 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 55
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    Biotechnology and Bioengineering 26 (1984), S. 392-393 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 56
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    Biotechnology and Bioengineering 26 (1984), S. 412-418 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pyridoxaminephosphate oxidase (EC 1.4.3.5, deaminating) that was partially purified about 40-fold from dry baker's yeast was immobilized to iodo- and bromoacetyl polysaccharides. The most effective carrier was an iodoacetyl cellulose, to which almost complete activity of pyridoxine 5′-phosphate oxidase was immobilized in 0.02M potassium phosphate buffer (pH 8.5) containing 2M ammonium sulfate at 4°C. The immobilized enzyme was more stable than the purified, soluble enzyme against heat and pH change. It was confirmed that N-(5′-phosphopyridoxyl)-L-serine was degradedly oxidized to pyridoxal 5′-phosphate and L-serine by the immobilized enzyme as comparable rate as pyridoxine 5′-phosphate, whereas N-(5′-phosphopyridoxyl)-D-serine did not serve as substrate, as in the purified, soluble enzyme.
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  • 57
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    Biotechnology and Bioengineering 26 (1984), S. 814-819 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 58
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    Biotechnology and Bioengineering 26 (1984), S. 820-823 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
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  • 59
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    Biotechnology and Bioengineering 26 (1984), S. 844-847 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article presents several characteristics of a state-of-the-art fermentation air filter. The filter medium is composed solely of PTFE and has an absolute pore size rating of 0.2 μm. Quantitative bacteria and bacteriophage retention is shown based on live organism challenge tests. A nondestructive filter test, correlated to the microorganism challenge tests and called the Forward Flow Integrity Test, is described. This test has a sensitivity of one part in 1012 and can be performed in situ.
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  • 60
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    Biotechnology and Bioengineering 26 (1984), S. 848-856 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The continuous slow feed of animal and vegetable oils is frequently found to be an economically attractive method for maintaining antibiotic fermentations at a highly productive rate. The sterilization of oil feeds can present a major problem in the production plant. In this article, we present data and methodology on the kinetics of the thermal sterilization of No. 2 lard oil and soybean oil. It was also determined that dry heat sterilization condition could occur if dry spores were added to dry oil. This condition could only be partially alleviated by the addition of water to the oil. The theory and design of a small tubular coil continuous sterilizer for sterilizing oils at the point of use is also presented. This type of sterilizer is economical and versatile and simplifies control and instrument requirements. It provides a realistic alternative to the use of sterile feed tanks and sterile headers.
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  • 61
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Proper design of fermentation facilities and equipment modification can control the risks associated with largescale production and purification of microbially produced cytotoxic agents and oncogenic viruses. The primary biohazard risks to operators and the environment are generation of aerosols and accidental spills. Fermentation and recovery facilities can be constructed to contain these agents by installing fermentation equipment within a HEPA-filter-exhausted biological barrier. Within this barrier system, large-scale processing that generates potentially hazaradous areosols (filtration, centrifugation of transformed cells or crystal slurries, and banding of viruses) should be isolated from other operations. Isolation of equipment is often required, with provision for both chemical and biological decontamination of process wastes. Failsafe fermentor over-pressure sensors, parallel exhaust gas filtration, welded transfer lines, and modified sampling systems for elimination of aerosols can be installed on most fermentation equipment. Aerosol and spill containment by proper equipment design, coupled with appropriate personnel protective equipment and medical monitoring, make possible safe production of experimental growth factors and viruses from large-scale culture of transformed mammalian cells and production of cytotoxic antitumor antibiotics.
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  • 62
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of pretreatment process variables [straw concentration between 20 and 90 kg volatile solids (VS)/m3, temperature between 30 and 85°C, and alkaline dosage between 0 and 80 g NaOH/kg VS] on acidogenesis and methanogenesis were investigated. Rates of acidogenesis and methanogenesis were determined using firstorder kinetics, and ultimate acid and methane yields were measured. The acid yield was not affected by pretreatment concentration or temperature, but increased as alkaline dosage increased. The acidogenesis rate was not affected by pretreatment temperature or alkaline dosage, but decreased as the substrate concentration increased. This decrease in the acidogenesis rate was attributed to a decrease in the inoculum: substrate ratio as the substrate concentration increased. The methane yield and methanogenesis rate were not affected by pretreatment substrate concentration or temperature, and both increased with alkaline dosage up to about 40 g NaOH/kg VS, then remained relatively constant above 40 g NaOH/kg VS.
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  • 63
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    Biotechnology and Bioengineering 26 (1984), S. 892-900 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Proteins have been immobilized in porous support particles held in a fixed-bed reactor through which protein solution is continuously circulated. Changing the recirculation flow rate alters the observed immobilization kinetics and the maximum enzyme loading which can be achieved for glucose oxidase and glucoamylase on carbodiimide-treated activated carbon and for glucoamylase immobilized on CNBr-Sepharose 4B. Direct microscopic examination of FITC-labelled protein in sectioned Sepharose particles and indirect activity-loading studies with activated carbon-enzyme conjugates all indicate that immobilized enzyme is increasingly localized near the outer surface of the support particles at larger recirculation flow rates. Restricted diffusion of enzymes may be implicated in this phenomenon. These contacting effects may be significant considerations in the scaleup of processes for protein impregnation in porous supports, since apparent activity and stability of the final preparation depend on internal protein distribution.
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  • 64
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    Biotechnology and Bioengineering 26 (1984), S. 901-904 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Immobilized β-galactosidase was obtained by crosslinking the enzyme with hen egg white using 2% glutaraldehyde. The gel obtained could be lyophilized to give a dry enzyme powder. The pH optimum of both the soluble and immobilized enzyme was found to be 6.8. The immobilized enzyme showed a higher Km for the substrates. The extent of enzyme inhibition by galactose was reduced upon immobilization. The stability towards inactivation by heat, urea, gamma irradiation, and protease treatment were enhanced. The bound enzyme as tested in a batch reactor could be used repeatedly for the hydrolysis of milk lactose. The possible application of this system for small-scale domestic use has been suggested.
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  • 65
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    Biotechnology and Bioengineering 26 (1984), S. 905-910 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inulin, a polyfruction, is found as the reserve carbohydrate in the roots and tubers of various plants (i.e. Jerusalem artichoke, chicory, and dahlia tubers). The β-fructofuranosidase (inulase) from the yeast Kluyveromyces fragilis is of interest because of its industrial potential in fructose syrup and alcohol production from inulin containing plants. We have found that the inulase of K. fragilis can be immobilized in the yeast cells by glutaraldehyde treatment. These cells are resistant to physical and enzymatic destruction. Although the exact nature of the immobilization is not fully understood, the kinetic parameters of the immobilized enzyme are similar to those of the soluble enzyme. No reduction of enzyme activity was observed after glutaraldehyde treatment and glutaraldehyde concentration did not affect enzyme activity. A 96% hydrolysis of dahlia inulin was achieved in 10.5 h with a 9.5% (w/v) fixed enzyme suspension. A Jerusalem artichoke extract containing 16.8%polyfructan was completely hydrolyzed in 3.5 h with a 0.24% (w/v)fixed enzyme suspension. This is a time frame feasible for industrial consideration.
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  • 66
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    Biotechnology and Bioengineering 26 (1984), S. 911-915 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An enzymatic method for the preparative resolution of racemic carnitine (whose L-isomer and its acyl-derivatives have numerous therapeutical applications) has been developed. It is based on our finding that electriceel acetylcholinesterase hydrolyzes the D- but not the L-isomer of acetylcarnitine. (Another cholinesterase tested, horse serum butyrylcholinesterase, is also stereospecific and hydrolyzes only the L-isomer of butyrylcarnitine.) Acetylcholinesterase, covalently attached to alumina, was employed for the resolution of D,L-carnitine; the latter was first chemically acetylated, then stereoselectively hydrolyzed with the immobilized enzyme, and finally the acetyl-L-carnitine and D-carnitine produced were separated by ion-exchange chromatography. Gram quantities of D,L-carnitine were thereby resolved.
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  • 67
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    Biotechnology and Bioengineering 26 (1984), S. 916-925 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Based on the material balance principle applied to microbial reactions in continuous bioprocesses, the concept of reaction rate control has been developed theoretically. This concept provides a more direct way of controlling biological activities than the control of physical or chemical parameters in practice today. From an analysis of dynamic and steady-state experiments, two control systems for carbon dioxide production rate control during the continuous culture of baker's yeast have been designed and evaluated experimentally. In these control methods, intracellular NADH concentration is used as an immediate indication of the onset of glucose repression. A more sophisticated master controller based on the respiratory quotient can be combined with these control methods. The resulting control system provides a means to indirectly optimize biomass production while preventing ethanol formation in the continuous culture of baker's yeast.
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  • 68
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    Biotechnology and Bioengineering 26 (1984), S. 926-935 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methods are presented for examining the consistency of experimental data for microbial growth where light energy is converted to chemical energy through photosynthesis. True growth yield and maintenance parameters are estimated for several sets of available experimental data. Methods of parameter estimation are presented which allow all of the measured variables to be used simultaneously for parameter estimation. The results show that a wide range of values have been found for the true growth yield and maintenance parameters. Values of the true growth yield range from 0.04 to values above those predicted by the Z-scheme model for photosynthesis.
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  • 69
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    Biotechnology and Bioengineering 26 (1984), S. 936-941 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two empirical models for the enzymatic hydrolysis of cellulose are used to analyze the same set of experimental data to determine if one model is superior to the other. Both models adequately describe the data. The parameters in both models may be correlated to the hydrolysis conditions of enzyme, substrate, and product inhibitor concentrations. Both empirical models have features which are consistent with theoretical models of cellulose hydrolysis.
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  • 70
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    Biotechnology and Bioengineering 26 (1984), S. 942-947 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simple operational strategy is shown to offer a viable means of enhancing plasmid stability in chemostat systems where plasmid loss is a common problem. Feedback control can be used to stabilize coexistence states, which are naturally unstable in the system investigated, and thus gurantee retention of the plasmid-carrying strain. The strategy exploits the normally undesirable characteristics of substrate inhibited growth kinetics, and is illustrated with specific reference to methanolutilizing organisms. Since the methodology may be easily implemented in practice, it offers an alternative to costly environmental methods such as antibiotic addition.
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  • 71
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    Biotechnology and Bioengineering 26 (1984), S. 583-589 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Enzymatic properties of Alcaligenes faecalis cells immobilized in polyacrylamide were characterized and compared with those reported for the extracted enzyme, and with those measured for free cells. Many of the properties reflected those of the extracted enzyme rather than those measured in the free whole cells prior to immobilization, suggesting cell disruption during immobilization. These properties included the pH activity profile, a slightly broader pH stability profile, and the activation energy. Electron micrographs showed evidence of cell debris among the polymer matrix. The immobilized cells were not viable, and did not consume glucose. Thermal stability was less after immobilization with a half-life of 16 h at 45°C, and 3.5 h at 50°C. The immobilized preparation was more stable when stored lyophilized rather than in buffer, losing 23 and 52% activity, respectively, after six months. The enzyme was irreversibly inhibited by both acetate and citrate buffers. If the immobilized enzyme is to be used in conjunction with cellulases from Trichoderma reesei for cellulase saccharification, the optimal conditions would be pH 5.5 and 45°C in a buffer containing no carboxylic acid groups.
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  • 72
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    Biotechnology and Bioengineering 26 (1984), S. 599-603 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new enzymatic method for the removal of phenols from industrial aqueous effluents has been developed. The method uses the enzyme polyphenol oxidase which oxidizes phenols to the corresponding o-quinones; the latter then undergo a nonenzymatic polymerization to form water-insoluble aggregates. Therefore, the enzyme in effect precipitates phenols from water. Polyphenol oxidase has been found to nearly completely dephenolize solutions of phenol in the concentration range from 0.01 to 1.0 g/L. The enzymatic treatment is effective over a wide range of pH and temperature; a crude preparation of polyphenol oxidase (mushroom extract) is as effective as a purified, commercially obtained version. In addition to phenol itself, polyphenol oxidase is capable of precipitating from water a number of substituted phenols (cresols, chlorophenols, naphthol, etc.). Also, even pollutants which are unreactive towards polyphenol oxidase can be enzymatically coprecipitated with phenol. The polyphenol oxidase treatment has been successfully used to dephenolize two different real industrial waste-water samples, from a plant producing triarylphosphates and from a coke plant. The advantage of the polyphenol oxidase dephenolization over the peroxidase-catalyzed one previously elaborated by the authors is that the former enzyme uses molecular oxygen instead of costly hydrogen peroxide (used by peroxidase) as an oxidant.
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  • 73
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    Biotechnology and Bioengineering 26 (1984), S. 604-612 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A dynamic mathematical model has been developed to describe microbial desulfurization of coal by Thiobacillus ferrooxidans. The model considers adsorption and desorption of cells on coal particles and microbial oxidation of pyritic sulfur on particle surfaces. The influence of certain parameters, such as microbial growth rate constants, adsorption-descrption constants, pulp density, coal particle size, initial cell and solid phase substrate concentration on the maximum rate of pyritic sulfur removal, have been elucidated. The maximum rate of pyritic sulfur removal was strongly dependent upon the number of attached cells per coal particle. At sufficiently high initial cell concentrations, the surfaces of coal particles are nearly saturated by the cells and the maximum leaching rate is limited either by total external surface area of coal particles or by the concentration of pyritic sulfur in the coal phase. The maximum volumetric rate of pyritic sulfur removal (mg S/h cm3 mixture) increases with the pulp density of coal and reaches a saturation level at high pulp densities (e.g. 45%). The maximum rate also increases with decreasing particle diameter in a hyperbolic form. Increases in adsorption coefficient or decreases in the desorption coefficient also result in considerable improvements in this rate. The model can be applied to other systems consisting of suspended solid substrate particles in liquid medium with microbial oxidation occurring on the particle surfaces (e.g., bacterial ore leaching). The results obtained from this model are in good agreement with published experimental data on microbial desulfurization of coal and bacterial ore leaching.
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  • 74
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    Biotechnology and Bioengineering 26 (1984), S. 613-619 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Batch growth tests were performed under both replicating and nonproliferating (no nitrogen source in medium) conditions with acclimated heterogenous populations that utilized phenol as a sole source of carbon and energy. It was shown that the acclimated populations could efficiently remove the toxic waste component phenol under nonproliferating conditions by utilizing an oxidative assimilation mechanism. The phenol was assimilated and converted into nonnitrogenous storage products. During the assimilation process, the cells had a tendency to excrete some product (nonsubstrate) chemical oxygen demand (COD). Bench-scale oxidative assimilation units were operated by sequentially feeding a carbon source (phenol) and nitrogen source (ammonium sulfate) to heterogeneous populations. This demonstrated that, subsequent to the addition of the nitrogen source to the medium, the cells utilized the stored carbon for replication. Four of these units were operated at different phenol COD-to-ammonia-nitrogen ratios of 10:1, 20:1, 40:1, and 50:1. All of these units demonstrated excellent removal of phenol using an oxidative assimilation mechanism. These results suggested the feasibility of utilizing a continuous flow oxidative assimilation process for the treatment of nitrogen-deficient phenolic wastes. This process would be advantageous over conventional treatment processes in that it would realize a savings in chemical costs (ammonia as nitrogen source) and prevent leakage of excess ammonia from the system.
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  • 75
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    Biotechnology and Bioengineering 26 (1984), S. 623-626 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
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  • 76
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 77
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    Biotechnology and Bioengineering 26 (1984), S. 1306-1312 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Frog epidermis tyrosinase has been immobilized on Enzacryl-AA (a polyacrylamide-based support) and CPGzirclad-Arylamine (a controlled pore glass support) in order to stabilize the tyrosine hydroxylase activity of the enzyme; in this way, the immobilized enzyme could be used to synthesize L-dopa from L-tyrosine. The activity immobilization yield YIMEact (higher than 86%), coupling efficiency (up to 90%), storage stability (no loss in 120 days), and reaction stability (t1/2 was higher than 20 h in column reactors) were measured for tyrosinase after its immobilization. The results showed a noticeable improvement (in immobilization yield, coupling efficiency, and storage and operational stabilities) over previous reports in which tyrosinase was immobilized for L-dopa production. The activity and stability of immobilized enzyme preparations working in three different reactor types have been compared when used in equivalent conditions with respect to a new proposed parameter of the reactor (Rp), which allows different reactor configurations to be related to the productivity of the reactor during its useful life time. The characteristic reaction inactivation which soluble tyrosinase shows after a short reaction time has been avoided by immobilization, and the stabilization was enhanced by the presence of ascorbate. However, another inactivation process appeared after a prolonged use of the immobilized enzyme. The effects of reactor type and operating conditions on immobilized enzyme activity and stability are discussed.
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  • 78
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    Biotechnology and Bioengineering 26 (1984), S. 1066-1070 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effectiveness of attaching flavin adenine dinucleotide (FAD) via a C bridge to Teflon-bonded carbon black (CB), and the subsequent immobilization of glucose oxidase on the FAD-modified electrodes has been studied by cyclic voltammetry. When FAD alone is bound to the electrode, it undergoes reduction and oxidation at -0.62 and -0.5 V, respectively - values similar to those obtained with free FAD. Compared to the free enzyme, the reduction of FAD as part of the immobilized enzyme is 200 mV more cathodic, while the oxidation potential remains the same in both cases.
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  • 79
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The massive conversion of δ-aminolevulinic acid (ALA) to protochlorophyllide (Pchlide) and the massive conversion of chlorophyllide a (Chlide a) to chlorophyll a (Chl a) are two essential conditions for the ALA-dependent assembly of photosynthetic membranes in vitro. In this work, we describe the development of a cell-free system capable of the forementioned biosynthetic activities at rates higher than in vivo, for the first 2 h of dark-incubation. The cell-free system consisted of (1) etiochloroplasts prepared from kinetin and gibberellic-acid-pretreated cucumber cotyledons, and (2) cofactors and additives described elsewhere and which are needed for the massive conversion of ALA to Pchlide, (3) high concentrations of ATP, MgCl2, and an isoprenol alcohol such as phytol, were required for the massive conversion of Chlide a to Chl a. An absolute and novel requirement of Mg2+ for the conversion of Chlide a to Chl a was also demonstrated. In addition to the role of phytol as a substrate for the conversion of Chlide a to Chl a, the data suggested that this alcohol may also be involved in the regulation of the reactions between ALA and Pchlide. It is proposed that during greening, the conversion of Chlide a to Chl a may follow different biosynthetic rates, having different substrate and cofactor requirements, depending on the stage of plastid development.
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  • 80
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    Biotechnology and Bioengineering 26 (1984), S. 1352-1363 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The growth dynamics of a methanol utilizing bacterium, L3, in batch bioreactors were experimentally investigated. Formaldehyde, a key intermediate of methanol oxidation, is indicated to have a significant role in the complex batch growth behavior of L3. The intricate batch growth dynamics of many microorganisms can be elegantly characterized by examining the specific rates of exchange of nutrients and products between the cells and the cellular environment. Following such an analysis, the batch growth of L3 on methanol was characterized by the presence of unbalanced and balanced growth phases. The nature and significance of nutrient and product concentration profiles or semilog-arithmic profiles of nutrient and product exchange rates during balanced and unbalanced growth phases are also outlined.
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  • 81
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    Biotechnology and Bioengineering 26 (1984), S. 508-512 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Addition of microcarrier beads to a matrix perfusion cell culture system allowed growth of anchorage dependent human foreskin fibroblasts which would not grow in the culture units alone. The utility of the system for collection of cellular products was demonstrated by the induction and harvesting of human (β) interferon. Interferon production was highest in perfusion cultures when medium was circulated throughout the induction and when inducer containing 100 μg/mL polyriboinosinic: polyribocytidylic acid was placed directly in contact with cells in the extracapillary space. These conditions provided 4-to-10-fold greater interferon yields per cell, and approximately 12-fold increases per vessel, than monolayer cultures. Perfusion grown cells produced interferon at a maximal level for 20 h postinduction compared to approximately 2 h for monolayer grown cells, thus giving a higher total yield of interferon. Other procedures increasing the efficiency of the system included priming with 50 U/mL interferon standard, reinduction of cells, use of antibiotic free medium, reduced serum concentrations, and in vitro aging of the cells.
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  • 82
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    Biotechnology and Bioengineering 26 (1984), S. 544-545 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 83
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    Biotechnology and Bioengineering 26 (1984), S. 1390-1392 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 84
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    Biotechnology and Bioengineering 26 (1984), S. 1395-1397 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 85
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    Biotechnology and Bioengineering 26 (1984), S. 1393-1394 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 86
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    Biotechnology and Bioengineering 26 (1984), S. 1398-1401 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
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  • 87
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    Biotechnology and Bioengineering 26 (1984), S. 1425-1429 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two-phase anaerobic digestion of liquid swine manure has been developed with options for single-cell protein (SCP) or methane production. In the acidogenic phase at two to four days retention time, and 2.5-7.0% dry matter (DM) concentration, 8-46% of the volatile solids was solubilized. Maximum reactor capacity was 3.86 g/L at 7.0% DM concentration, but optimal operation was achieved at 4.5% DM concentration at four days retention time. The second methanogenic phase was operated continuously and had a maximum specific methane production rate of 0.70 L/L day at 12 days retention time. With recirculation, the rate was 1.16 L/L day at 8.5 days retention time with 52.7% conversion of organic matter. Maximum digestibility was 66% of the lignin free organic matter.
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  • 88
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    Biotechnology and Bioengineering 26 (1984), S. 1430-1435 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article presents a clear experimental determination of the behavior of nutrient uptake rate, mean cell nutrient content, and specific growth rate following the injection of pulses of additional limiting nutrient into a chemostat culture of Chlamydomonas reinhardii. The uptake rate per cell is a hyperbolic function of external nutrient concentration. The specific growth rate is related to the mean cell nutrient content by a hysteresis loop. The data obtained is used to test the performance of the Caperon-Droop mean cell quota model. It is demonstrated that this model cannot be used under severe transient conditions, even when modified by the introduction of a discrete time delay, a simple memory function, or time-dependent intracellular nutrient processing.
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  • 89
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    Biotechnology and Bioengineering 26 (1984), S. 1436-1444 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In many anaerobic fermentation processes, high energy bonds in adenosine triphosphate (ATP) are produced when available electrons are converted from organic substrate into extracellular organic products such as ethanol. The true growth yield and maintenance parameters are directly related to the product formation kinetic parameters for these anaerobic processes. Methods are presented which allow all of the experimental measurements to be used simultaneously to estimate these parameters. Results are presented for several different anaerobic fermentations.
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  • 90
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lipase from Candida cylindracea has been found to be a highly stereospecific catalyst suitable for preparative resolution of racemic acids and alcohols. Using (R, S)-2-(p-chlorophenoxy) propionic acid (whose R isomer is a herbicide) and (R, S)-sec-butanol (a versatile synthon) as model compounds, three alternative approaches to lipase-catalyzed resolutions - asymmetric hydrolysis, esterification, and transesterification - have been compared. Enzymatic esterification in biphasic systems has been ruled out for preparative resolutions because addition of the acids lowers the pH of the aqueous phase thereby greatly reducing the efficiency of the procedure. Both enzymatic hydrolysis and biphasic transesterification afforded resolution of the racemates on a gram scale. From the standpoint of productivity, ease of product separation, and the amount of steps required, lipasecatalyzed asymmetric hydrolysis has been judged to be superior for the practical resolution of racemic acids, and lipase-catalyzed asymmetric transesterification to be the method of choice for the practical resolution of racemic alcohols.
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  • 91
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    Biotechnology and Bioengineering 26 (1984), S. 1475-1484 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Enzymatic corn starch liquefaction with α-amylase was carried out. Molecular weight distributions of the resulting hydrolysates are presented using aqueous size exclusion chromatographic techniques. It is demonstrated that despite the fact that the enzyme employed reacts in a random endoacting manner, the product distributions are nonrandom. The results are explained in part by a multimerization process whereby the polymeric substrate molecules preferentially associate, forming intermolecular aggregates. These aggregates are either a consequence of the manner in which the material is deposited into the native granular structure of starch or due to intrinsic physical chemical properties of the polysaccharide. In the latter case, the results are shown to correspond to known multimerized amylose, although complete characterization of the polysaccharide is currently not available. The results presented are used to develop a simplified kinetic model of starch liquefaction and shown to simulate the product distributions accurately.
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  • 92
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The design and operation of an industrial penicillin-V deacylation reactor is simulated, using a kinetic expression and mass transport parameters for the immobilized enzyme particles which were determined experimentally in a previous study. It is desirable to use a series of equalsized plug flow reactors with pH control at the entrance to each reactor, and with a possibility of recycling reactant in each reactor. These measures are necessary to avoid a steep pH profile through the reactor; the deacylation reaction is accompanied by an increase of acidity of the reaction medium, and H+ is a strong inhibitor and may deactivate the enzyme. The optimization study which is carried out at a fixed penicillin conversion of x = 0.99 shows that it is uneconomical to use penicillin feed concentrations above 150mM-175mM, and that the buffer concentration in the reaction medium should not be less than 50mM-75mM. Increasing the number of reactors from 4 to 8 or 10 leads to higher productivity of 6-APA, and a moderate recycle in the first couple of reactors diminishes the sharp decrease in pH which will be found in a straight plug flow reactor operation of the equipment. Higher pumping costs and lower productivity are unavoidable drawbacks of an operation mode where the separation costs for the product mixture are desired to be low.
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  • 93
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    Biotechnology and Bioengineering 26 (1984), S. 1498-1505 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Removal of hemicellulose by acid pretreatment in a flow reactor followed by enzymatic hydrolysis of the neutralized slurry has resulted in glucose yields as high as 95% for mixed hardwood. For white pine, however, the maximum glucose yield is 65%. Although pine has a higher extractives content, removal of the extractives prior to enzymatic hydrolysis does not increases the glucose yield. Pore size measurements reveal that the increase in pore volume, in the size range of the cellulase molecule, following pretreatment for pine is only about one-half the value obtained with mixed hardwood. This suggests that pore volume is an important determinant of substrate-enzyme reactivity.
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  • 94
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    Biotechnology and Bioengineering 26 (1984), S. 1140-1140 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 95
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    Biotechnology and Bioengineering 26 (1984), S. 670-676 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of alcohol/water/catalyst mixtures to delignify wood allows the lignin to be recovered in a usable form while leaving the carbohydrate fraction relatively intact. The effects of temperature, reaction time, and the type of solvent and catalyst on the delignification of milled poplar wood were investigated. The lignin, cellulose, and hemicellulose composition of the pretreated material was measured for each treatment condition. In addition, the pretreated samples were subjected to enzymatic hydrolysis using the cellulases produced by the thermophilic bacterium Thermomonospora sp. YX. The extent of enzymatic hydrolysis was characterized using an empirical model, and the results were used to examine the effectiveness of the pretreatment.
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  • 96
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    Biotechnology and Bioengineering 26 (1984), S. 682-686 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article derives a number of equations which can be used in both continuous and the semicontinuous cultures of microorganism populations in chemostat systems. Using these equations, some phenomena which have been known for many years can be explained reasonably in terms of chemical kinetics, and a number of analytical solutions can be obtained instead of numerical solutions previously published.
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  • 97
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    Biotechnology and Bioengineering 26 (1984), S. 687-690 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The refractory organic sulfur compound dibenzothiophene (DBT) has been oxidized by the thermophilic, sulfur oxidizing organism Sulfolobus acidocaldarius. Sulfate ions were released into the medium as the oxidation product. The kinetics of this oxidation have been investigated on the basis of sulfate released as a result of oxidation. Dibenzothiophene was found to be inhibitory to the organisms for initial concentrations over 500 mg/L. The organism may prove to be capable of oxidizing thiophene compounds present in oil refinery wastewater, coal, and crude oil.
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  • 98
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    Biotechnology and Bioengineering 26 (1984), S. 677-681 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Chlorella sp. strain VJ79 was isolated from a total heterotrophic count of a wastewater collector. It grows autotrophically, heterotrophically, and mixotrophically on a variety of organic substrates. Glucose and serine promote a mixotrophic growth from which the yield is higher than the sum of autotrophic and heterotrophic yields, but serine assimilation requires light. The interaction of glucose and light was studied in proliferating and nonproliferating cells by respirometry (IRGA and Warburg) and growth experiments. Glucose inhibits the photosynthetic CO2 fixation ten-fold and modifies the pigmentary system as it does in heterotrophic cultures. Light inhibits glucose uptake and assimilation, but under mixotrophic conditions maximal utilization of glucose is obtained. Mutants defective in autotrophic growth were isolated by mutagenesis with nitrosoguanidine. They show a degenerated pigmentary system and a mixotrophic growth yield equal to that of the heterotrophic growth. The analysis of the mixotrophic system shows that light energy, dissipated during autotrophic growth, is used under mixotrophic conditions. From the increase in growth, the increase in photosynthetic efficiency can be calculated as ca. sixfold.
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  • 99
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    Biotechnology and Bioengineering 26 (1984), S. 691-698 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A theoretical description of a low-frequency, dual-source acoustic treatment of protein precipitates is presented. Two mechanisms for the potential improvement of the centrifugal separation of precipitates are proposed. They are acoustic aggregation, which causes an increase in particle size, and aggregate deformation, which results in an increase in aggregate density. Experiments with isoelectric soya protein precipitate indicated that the extent of ageing prior to acoustic conditioning is important. Support for both aggregation and dewatering was found and a maximum increases in the particle settling velocity of 20% was observed.
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  • 100
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    Biotechnology and Bioengineering 26 (1984), S. 699-701 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Wood waste powder from Tectona grandis containing melanin was less susceptible to enzymatic hydrolysis than powder without melanin. About a 53% increase in saccharification was noted when melanin was removed. Melanin caused inhibition to all cellulolytic enzymes, but in different degrees. Endo-β-1,4-glucanase and β-glucosidase were markedly inhibited when melanin was preincubated with enzyme, while exo-β-1,4-glucanase was severely inhibited when melanin was preincubated with substrate. The latter was found to be dependent on the contact time. The activities of endo-β-1,4-glucanase and β-glucosidase were noncompetitively inhibited by melanin.
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