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  • 1
    Digitale Medien
    Digitale Medien
    Temporal and spatial variability of reduced sulfur species (FeS2, S2O3 2−) and porewater parameters in salt marsh sediments (1991)
    Springer
    Biogeochemistry 14 (1991), S. 57-88 
    Details
    ISSN: 1573-515X
    Schlagwort(e): Dissolved sulfur species ; inorganic solid sulfur ; pyrite ; salt marshes ; soluble iron ; short term changes ; 210Pb ; 137Cs ; 7Be
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract Porewater species and solid inorganic sulfur speciation were measured before and after the spring tide (which occurs over a 6–7 day period) during a portion of the summer seasons of 1987, 1988 and 1989 in Great Marsh, Delaware. Samples were taken from two locations in the marsh (near creek and mid-marsh) inhabited by the short form of Spartina alterniflora. In 1987, pyrite and thiosulfate decreased over the spring tide. Other porewater species also underwent large changes in concentration — in some cases order of magnitude. However, in 1988 and 1989, there was no evidence for short term changes of pyrite. In 1988, drought conditions were prevalent throughout the sampling whereas in 1989 wet conditions were prevalent. Porewater parameters demonstrated that oxidation was extensive during the sampling period in 1988 and related to dessication. Both climatic and spring tidal flooding conditions have a pronounced affect on the chemistry of the system. Data from atmospherically derived radionuclides (210Pb,137Cs,7Be) indicate that bioturbation is not as important at the mid-marsh site as at the near creek site. Porewater chloride and7Be data support infiltration of overlying waters at both sites. The decrease in pyrite over the spring tide in the 1987 samples is related to oxidation. The possible oxidants are discussed and Fe(III) is the favored direct oxidant based upon a review of field and laboratory data. Iron(III) was measured in several filtered porewater samples. However, we cannot indicate with certainty that the Fe(III) is always soluble. The Fe(III) measured may be colloidal or complexed. Pyrite oxidation is noted when the Fe(III) to Fe(II) ratio, pH and alkalinity are all low.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00000886
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  • 2
    Digitale Medien
    Digitale Medien
    Seasonal cycling of Fe in saltmarsh sediments (1995)
    Springer
    Biogeochemistry 29 (1995), S. 159-181 
    Details
    ISSN: 1573-515X
    Schlagwort(e): iron ; microbial mat ; porewater ; pyrite ; sedimentary geochemistry ; Spartina alterniflora ; sulfur
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract This study combines an analysis of porewater chemistry with new, solid phase wet chemical extractions to examine the seasonal cycling of Fe in vegetated and unvegetated (cyanobacterial mat) saltmarsh sediments. Saltmarsh sediments are shown to contain more solid phase reactive Fe than other marine sediments studied so far. From the partitioning and speciation of solid Fe, and solid/soluble reduced S analysis in 10 sediment cores, we have observed that a majority of solid Fe in these sediments is cycled rapidly and completely between oxidized reactive Fe and reduced Fe as pyrite. Vegetated porewaters showed a lower pH and much higher Fe(II) concentrations on average than unvegetated porewaters in the top 10 cm, whereas sulfate, alkalinity, and sulfide concentrations were similar in the two environments. The amorphous Fe(III) oxide fraction showed a high negative correlation to solid and soluble reduced S (r 2 = −0.86 and −0.71, respectively) in surface vegetated sediments whereas the crystalline Fe(III) oxide fraction showed a high negative correlation (r 2 = −0.96) to sulfide only at depth. Though reactive Fe was observed in unvegetated sediments, no seasonal trend was apparent and the speciation of solid Fe revealed that most of it was reduced. Solid phase and porewater chemistry support the dominant role of the biota (Spartina alterniflora and bacteria) in controlling the reactivity of Fe and suggest that the current definition of solid phase, reactive Fe should be expanded to include crystalline Fe(III) minerals which are available for pyrite formation in saltmarsh sediments. In support of previous saltmarsh studies, we present evidence that the redox cycle of solid Fe is controlled by sulfate reduction and sediment oxidation which respond to both annual cycles (light, temperature) and to short-term, episodic effects such as weather and tides.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00000230
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  • 3
    Digitale Medien
    Digitale Medien
    “Stresscoat” deformation studies of the human femur under transverse loadingThis investigation was supported (in part) by Researeh Grant 1925 (C2) from the National Institutes of Health, United States Public Health Service. (1953)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 116 (1953), S. 171-187 
    Details
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ar.1091160206
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  • 4
    Digitale Medien
    Digitale Medien
    Pituitary tumorigenesis in aging female C57BL/6J mice: A light and electron microscopic study (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 199 (1981), S. 423-432 
    Details
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Spontaneous pituitary tumors have been studied by light and electron microscopy in female C57BL/6J mice at 2½, 11, 15, 22, 23, 24 and 30 months. Tumors were evident macroscopically in greater than 50% of mice 22 months or older, and greater than 80% on microscopic evaluation. Active and hypertrophied mammotrophs were the predominant cell type within the tumors at 22--30 months, often totally filling large portions of the tumor mass. Exocytosis of secretory granules was extensive from the mammotrophs, but much less abundant from other parenchymal cells. Somatotrophs and gonadotrophs were also present, and appeared active and often strikingly hypertrophied. The tumors were characterized by disruptions of parenchymal and capillary integrity which resulted in the formation of large vascular lakes lined solely by tumor cells, generally mammotrophs. Apparent metastasis of tumor cells into the vascular lakes was also observed. In 11- and 15-month mice small tumors or pretumor foci were evident in some mice on microscopic evaluation, although they were not visible macroscopically. Their degree of development was somewhat variable, but they had essentially the same features as more advanced tumors in older mice. Pretumor foci were characterized by more moderate disruptions of parenchymal cell and capillary integrity; cellular hypertrophy, particularly of somatotrophs and gonadotrophs; and the presence of small vascular lakes. In 2½-month mice tumors could not be localized macroscopically or microscopically, and the pituitary was composed of well-defined cell cords and an intact capillary bed. However, small focal zones of capillary and tissue disruption were apparent occasionally in 2½-month mice. These findings indicate that the process of pituitary tumorigenesis in female C57BL/6J mice is initiated by midlife, with subsequent progressive development into large, mammotroph-dominated tumors.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/ar.1091990310
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  • 5
    Digitale Medien
    Digitale Medien
    Number of adrenergic and Islet-1 immunoreactive cells is increased in avian trunk neural crest cultures in the presence of human recombinant osteogenic protein-1 (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 203 (1995), S. 434-447 
    Details
    ISSN: 1058-8388
    Schlagwort(e): BMP-7 ; Bone morphogenetic protein ; TGF-β superfamily ; Neural differentiation ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: OP-1, also known as BMP-7, is a member of the TGF-β superfamily of proteins and was originally identified on the basis of its ability to induce new bone formation in vivo. OP-1 mRNA is found in the developing kidney and adrenal gland as well as in some brain regions (Özkaynak et al. [1991] Biochem. Biophys. Res. Commun. 179:116-123). We have tested the effect of recombinant human OP-1 on quail trunk neural crest cultures. The number of catechol-amine-positive cells which developed after 7 days in vitro in the presence of OP-1 was increased in a dose-dependent manner, with a greater than 100-fold maximal stimulation observed. The increase in the number of catecholamine-positive cells in the presence of OP-1 was paralleled by an increase in the number of tyrosine hydroxylase (TH)-positive cells. In contrast, total and melanocyte cell number were unaffected by the presence of OP-1. The number of Islet-1-immunoreactive cells was also increased by OP-1, but to only about half the value seen for TH. Double label experiments revealed these Islet-1-positive cells were a subset of the TH-positive cells. Inhibitors of DNA synthesis prevented the OP-1-mediated increase in adrenergic cell number, indicating that OP-1 does not act on a postmitotic cell population. However, labeling studies with bromodeoxyuridine indicated that OP-1 did not increase the proportion of the cell population engaged in DNA synthesis. Thus, the OP-1-mediated increase in adrenergic cell number most likely occurs as a result of the enhanced survival of a subpopulation of adrenergic precursors or an increase in their probability of adrenergic differentiation, but not by increasing the mitotic rate of adrenergic precursors or adrenergic cells themselves. In contrast to OP-1, TGF-β1 decreased adrenergic cell number. When OP-1 and TGF-β1 were added simultaneously, TGF-β1 antagonized the OP-1-mediated increase in adrenergic cell number in a dose-dependent manner. ©1995 Wiley-Liss, Inc.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aja.1002030406
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  • 6
    Digitale Medien
    Digitale Medien
    Development of the vasculature of the anterior pituitary: Ontogeny of basic fibroblast growth factor (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 197 (1993), S. 81-93 
    Details
    ISSN: 1058-8388
    Schlagwort(e): Fibroblast growth factor ; Phagocytes ; Folliculostellate cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: This study correlates the ontogeny of basic fibroblast growth factor (FGF) with the development of the vasculature of the anterior pituitary (AP) in two strains of rat, Sprague-Dawley (SD) and Fischer 344 (F344). Immunolocalization of FGF was followed from the first appearance of Rathke's pouch (RP) in 12-day (12d) fetuses, through each day of fetal development, and in 5, 20, and 50d postnatal female rats. In addition, the ontogeny of folliculo-stellate cells (FSC) is described, since previous studies suggested that these unique cells might function as phagocytes in the regulation of FGF. In both rat strains, vascularization of the AP commenced in 16d fetuses. In 15-20d fetuses, dense foci of immunopositivity for extracellular FGF were apparent at sites of capillary penetration adjacent to partially disrupted, immature gonadotropes. Localization of FGF was first detected in immature gonadotropes in 18d fetuses and persisted in the cytosol of a subpopulation of gonadotropes thereafter. In 15d fetuses, FGF was localized within the cytosol intimately associated with the peripheral-facing plasma membranes of all cells of the adenohypophysis, and persisted to variable degrees in later fetal stages. Localization of FGF within nuclei of AP parenchymal cells was evident only in 16-17d fetuses. Although the ontogeny of FGF and vascularization of the AP was very similar in both rat strains, the ontogeny of FSC differed markedly. In both strains, follicular lumens contained FGF during late fetal and early postnatal development. However, both electron microscopy and immunostaining for S-100 marker protein revealed that the postero-lateral edges of the AP of F344 rats often lacked FSC when compared to SD rats, a situation which could compromise regulation of FGF by FSC at the AP periphery in that strain, and thereby contribute to the neovascularization from systemic blood vessels known to occur in that strain during prolactinoma formation. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 23 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aja.1001970202
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  • 7
    Digitale Medien
    Digitale Medien
    Cations in the rat pars distalis ultrastructural localizationSupported in part by: HEW-NIH Grant CA 14089. Los Angeles County/USC Cancer Center. (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 146 (1976), S. 189-206 
    Details
    ISSN: 0002-9106
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Pituitary glands of female Sprague Dawley rats were fixed using the potassium pyroantimonate-osmium tetroxide technique by immersion or vascular perfusion. Both fixation procedures resulted in similar patterns of cation localization visualized as electron-dense precipitate within cells of the pars distalis. Nuclei were prominent sites of localization. Cytoplasmic precipitate occurred in association with the endoplasmic reticulum, typically within the cisternal spaces, and also was localized within the mitochondrial matrix and cristae, as well as Golgi membranes, small Golgi-associated vesicles, and multivesicular bodies. Immature secretory granules often contained precipitate between the core material of the granule and the enclosing smooth membrane. Frequently small antimonate-containing vesicles bordered the immature secretory granules. Precipitate was variable in secretory granules of more mature appearance although precipitate was apparent occasionally just within a granule's enclosing membrane. Granules closest to the plasma membrane often contained increased amounts of precipitate and small vesicles containing precipitate were observed fusing with them. Instances of granule release by emiocytosis often revealed a clustering of precipitate behind the core material away from the emiocytotic stoma, as well as at the stoma and frequently an increased electron density of filamentous material radiating from the granules' enclosing membranes or from the adjacent plasma membrane. Exposure of section material to the chelating agents EGTA and EDTA indicate that calcium is the primary cation localized within the cytoplasm of these secretory cells. These findings are consistent with a role for calcium as a facilitator in the processes of transport and release of secretory granules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aja.1001460207
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  • 8
    Digitale Medien
    Digitale Medien
    Development of the vasculature of the pars distalis in a tumor-susceptible strain of rat (Fischer 344) differs from vascular development in a non-tumor-susceptible strain (Lewis) (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 188 (1990), S. 297-306 
    Details
    ISSN: 0002-9106
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The development of the vasculature of the pars distalis of two strains of rat, Fischer 344 (F344) and Lewis (LEW), was followed in 16-day (16d) and 20-day (20d) fetuses, and in 1-day (1d), 5d, 20d, 50d, and 6-month-old females. No differences in the two strains were apparent in 16d fetuses; and the capillaries that were present were immature, i.e., tall, non-fenestrated endothelial cells, and were surrounded by poorly delineated pericapillary spaces. Immature capillaries also were predominant in 20d fetuses of both strains. Agranular folliculo-stellate cells were identifiable, projecting endfeet to the parenchymal basal lamina in 20d F344 fetuses, but not in LEW fetuses.Postnatally, the capillaries of LEW rats became progressively more thin-walled and fenestrated, and were surrounded by a pericapillary space that was well delimited by basal laminae at 20d. In 50d and 6-month LEW rats, capillaries were intact and surrounded by well-defined pericapillary spaces. By comparison in F344 rats, the capillaries remained more immature even in 50d rats and older. In addition, in F344 rats focal disruptions in endothelial cells and disruptions in parenchymal and capillary basal laminae were present in all postnatal stages, and a dramatic accumulation of plasma was evident within the pericapillary spaces at 20d. Endfeet processes of folliculo-stellate cells were abundant at the parenchymal basal lamina of 1d and 5d F344 neonates, but only rarely were identified in LEW neonates. Some activation of folliculo-stellate cells, i.e., increased numbers of lysosomes and dilated endoplasmic reticulum, was present in 50d F344 rats. Connective-tissue cells within the pericapillary space also were numerous and activated in F344 rats. Discrete gaps in the parenchymal basal lamina were evident subjacent to the folliculo-stellate cell endfeet in F344 rats but not in LEW rats.The vascular bed of F344 rats differs in its development from that of LEW rats. Characteristic of the F344 strain is a persistence of more immature capillaries, an inherent vascular fragility, and an activated state of folliculo-stellate cells.
    Zusätzliches Material: 73 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aja.1001880308
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