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  • Articles  (37)
  • Rat  (23)
  • nonlinear programming  (14)
  • Springer  (37)
  • 1975-1979  (37)
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  • Articles  (37)
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  • Springer  (37)
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  • 1
    Electronic Resource
    Electronic Resource
    Appearance of tyrosine hydroxylase, aromatic amino-acid decarboxylase, dopamine β-hydroxylase and phenylethanolamine N-methyltransferase during the ontogenesis of the adrenal medulla (1979)
    Springer
    Cell & tissue research 200 (1979), S. 1-13 
    Details
    ISSN: 1432-0878
    Keywords: Catecholamine synthesizing enzymes ; Adrenal medulla ; Embryonic induction ; Adrenocortical hormones ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cellular localization of the enzymes tyrosine hydroxylase (TH), aromatic amino-acid decarboxylase (or dopa decarboxylase, DDC), dopamine β-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) in the adrenal medulla of adult rats and rat fetuses (14th, 17th, 18th, 19th and 21st day) was examined. In the prenatal stages the medullary blastema and an adjacent part of the primitive sympathetic trunk were also investigated. Tissues were fixed in ice-cold 4% paraformaldehyde in 0.1 M phosphate buffer (pH 7.2). Cryostat sections (10 μm in thickness) were stained by the indirect immunofluorescence technique. Rabbit antibodies to TH (isolated from human pheochromocytoma), DDC, DBH and PNMT (the latter three isolated from bovine adrenal medulla) were used. Sections incubated with serum of non-immunized rabbits were used as controls. In the adult adrenal medulla, two cell types can be distinguished. One cell type contains only TH, DDC and DBH. The other cell type contains PNMT in addition. It is concluded that these cells correspond to the noradrenaline-(NA-) and adrenaline-(A-)storing cells respectively. In all prenatal stages TH, DDC and DBH are found in the primitive sympathetic trunk, in the medullary blastema, and in the medullary cells which have migrated into the cortical “anlage”. PNMT is observed for the first time on the 18th day. Moreover, PNMT could only be demonstrated inside the adrenal gland. From these observations it is concluded that the capacity to synthesize NA is developed even before the “medullary” cells have reached the cortical “anlage”. On the contrary, the capacity to synthesize A seems to be acquired only after this contact is established. The hypothesis is put forward that this phenomenon might indicate the induction of PNMT by glucocorticoids secreted by the fetal cortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236882
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  • 2
    Electronic Resource
    Electronic Resource
    Fine structure of the corpus luteum of the autografted ovary in the rat (1976)
    Springer
    Cell & tissue research 171 (1976), S. 375-379 
    Details
    ISSN: 1432-0878
    Keywords: Corpus luteum ; Autografts ; Rat ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The rat ovary has been transplanted successfully to subcutaneous tissue areas by several investigators. Light microscopy has revealed that corpora lutea in ovarian autografts are formed by luteinization of intact follicles and contain entrapped ova. In the present study, corpora lutea from autografted ovaries in castrate rats were obtained at metestrus and examined electron microscopically to determine whether their cellular morphology correlated with the normal progesterone levels in these animals. Cellular features usually accepted as regressive were apparent. The findings suggest either structural luteolysis is occurring before functional luteolysis or that the adrenal has increased steroidogenic activity in the castrate with ovarian autografts to account for the normal progesterone levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224661
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  • 3
    Electronic Resource
    Electronic Resource
    Specific arrangements of membrane particles at sites of exo-endocytosis in the freeze-etched neurohypophysis (1976)
    Springer
    Cell & tissue research 165 (1976), S. 317-325 
    Details
    ISSN: 1432-0878
    Keywords: Exocytosis, endocytosis ; Freeze-etching ; Electron microscopy ; Membrane particles, rosettes ; Neurohypophysis, neurosecretion ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Images have been obtained from freeze-etch replicas of neurohypophyses which are consistent with the view that orderly arranged aggregates of membrane particles occur in regions where fragments of membrane are being added to and taken away from the plasma membrane during secretion. Aggregates of particles included rosette-like and necklace-like patterns similar to those described by other authors at sites of exocytosis and endocytosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222436
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  • 4
    Electronic Resource
    Electronic Resource
    The pit cell: Description of a new type of cell occurring in rat liver sinusoids and peripheral blood (1976)
    Springer
    Cell & tissue research 173 (1976), S. 423-435 
    Details
    ISSN: 1432-0878
    Keywords: Liver ; Rat ; Sinusoid ; Pit cell ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pit cells — a new type of cell first described here and so named because they contain highly characteristic granules — are situated in the wall of rat liver sinusoids, and have hyaloplasmic pseudopodia intermingling with the microvilli of the parenchymal cells. The characteristic granules are mainly situated at one side of the nucleus, the other side showing organelle-free hyaloplasm. Pit cells are also found in portal tracts and in granuloma-like cellular aggregates. They also occur in rat peripheral blood, although there are morphological differences between cells in these two sites. Pit cells can be regarded as regular inhabitants of the sinusoidal wall, and therefore belong to the series of sinusoidal cells, i.e., the endothelial (Wisse, 1972), Kupffer (Widmann et al., 1972; Wisse and Daems, 1970; Wisse, 1974a,b), and fat-storing cells (Ito, 1973). Pit cells do not phagocytose and do not react to a great number of experimental conditions, to which endothelial and Kupffer cells do react (Wisse, 1972, 1974b). Mitosis has been observed in a pit cell. The function of pit cells remains obscure, but an endocrine function is suggested by the morphology of their highly characteristic granules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224305
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  • 5
    Electronic Resource
    Electronic Resource
    Extraneuronal effects of 6-hydroxydopamine (1976)
    Springer
    Cell & tissue research 174 (1976), S. 83-97 
    Details
    ISSN: 1432-0878
    Keywords: 6-hydroxydopamine ; Extraneuronal effects ; Rat ; Adrenal ; Tissue culture ; Electron microscopy ; Microspectrofluorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of various concentrations of 6-hydroxydopamine (6OHDA) on rat adrenocortical cells in tissue culture were studied with phase contrast and electron microscopy. With 40 mg/l of 6-OHDA the first signs of alteration as revealed by microcinematography appeared in isolated cortical cells as early as 15 min after addition of the drug. There was a cessation of movement of cell organelles and an immobilisation of membrane undulations followed by the development of dark inclusion bodies. The cells underwent increasing shrinkage and collapsed by 11/2 h. Chromaffin cells were not affected until 45 min after exposure to the drug and neurons were the most resistant population. However 61/2 h after application of the drug most cells in the culture were dead. 6-OHDA applied in different doses and to adrenal expiants did not alter the sequence of events. Ultrastructurally cortex cells underwent damage along two lines: they either showed lytic changes or developed various types of dense bodies before reaching the lytic stage. Treatment of cortical cells with 40 mg/l 5-or 6-OHDA followed by exposure to buffered 2% glyoxylic acid and heat did not produce a fluorescence within the cells. Microspectrofluorimetry on amine models with noradrenaline, 5- and 6-OHDA revealed that neither 5-nor 6-OHDA are capable to form a fluorophore with glyoxylic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222152
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  • 6
    Electronic Resource
    Electronic Resource
    Intercellular attachments between calcified collagenous tissue forming cells in the rat (1978)
    Springer
    Cell & tissue research 191 (1978), S. 507-512 
    Details
    ISSN: 1432-0878
    Keywords: Odontoblasts ; Osteoblasts ; Cementoblasts ; Intercellular attachments ; Electron microscopy (SEM/TEM) ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Osteoblasts of the young rat cranium, and cementoblasts and odontoblasts of young rat molars were prepared by ethanol freeze-fracture prior to critical point drying for scanning electron microscopy (SEM) as well as conventional transmission electron microscopy (TEM) techniques. Critical point drying causes shrinkage which separates the lateral intercellular contacts between neighbours in the same sheet in the case of cementoblasts and osteoblasts, but not those between odontoblasts. These differences are considered to be of functional significance and need to be taken into consideration when formulating theories of calcium influx into the mineralizable matrix of the respective tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219813
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  • 7
    Electronic Resource
    Electronic Resource
    Optimality conditions and constraint qualifications in Banach space (1975)
    Springer
    Journal of optimization theory and applications 15 (1975), S. 667-684 
    Details
    ISSN: 1573-2878
    Keywords: Necessary conditions ; mathematical programming ; Banach spaces ; optimization theorems ; nonlinear programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper, necessary optimality conditions for nonlinear programs in Banach spaces and constraint qualifications for their applicability are considered. A new optimality condition is introduced, and a constraint qualification ensuring the validity of this condition is given. When the domain space is a reflexive space, it is shown that the qualification is the weakest possible. If a certain convexity assumption is made, then this optimality condition is shown to reduce to the well-known extension of the Kuhn-Tucker conditions to Banach spaces. In this case, the constraint qualification is weaker than those previously given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00935506
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  • 8
    Electronic Resource
    Electronic Resource
    A computational study of methods for solving polynomial geometric programs (1976)
    Springer
    Journal of optimization theory and applications 19 (1976), S. 233-259 
    Details
    ISSN: 1573-2878
    Keywords: Geometric programming ; signomial functions ; computing methods ; nonlinear programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A computational comparison of several methods for dealing with polynomial geometric programs is presented. Specifically, we compare the complementary programs of Avriel and Williams (Ref. 1) with the reversed programs and the harmonic programs of Duffin and Peterson (Refs. 2, 3). These methods are used to generate a sequence of posynomial geometric programs which are solved using a dual algorithm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00934095
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of 1-alpha-hydroxyvitamin D3 on osteoporosis in rats induced by oophorectomy (1979)
    Springer
    Calcified tissue international 27 (1979), S. 161-164 
    Details
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Ovary ; Rat ; Vitamin D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Fifty adult female rats were used to study the effect of 1-alpha-hydroxyvitamin D3 (1α-OH-D3)on bone after oophorectomy. The experimental period was 6 months. At the end of the experiment the femurs and the tibias were investigated for bone mass and composition. Significant signs of osteopenia occurred as a result of oophorectomy. The treatment with 1α-OH-D3 induced only minor changes in blood chemistry but increased bone mass significantly. The findings support the view that 1α-OH-D3 may be a valuable tool in the treatment of osteoporosis resulting from ovarian insufficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441179
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  • 10
    Electronic Resource
    Electronic Resource
    Rate of protein synthesis in rat salivary gland cells after pilocarpine or feeding (1975)
    Springer
    Cell & tissue research 164 (1975), S. 447-456 
    Details
    ISSN: 1432-0878
    Keywords: Protein secretion ; Protein synthesis ; Salivary glands ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of pilocarpine and food uptake on the rate of incorporation of [3H]-leucine in vivo was measured by means of quantitative radioautography in three exocrine cells of the rat: the acinar and the granular duct cells of the submandibular and the acinar cells of the parotid gland. The three cell types react differently. The submandibular acinar cells showed a decrease in incorporation rate after pilocarpine administration but not after feeding. The incorporation rate of the granular duct cells of the submandibular gland remains constant after both stimulations. The acinar cells of the parotid gland show an increase in incorporation rate of [3H]-leucine in response to both. The contrast between the submandibular and the parotid gland could also be demonstrated radiobiochemically, the results reflecting the incorporation rates of the acinar cells of both glands, giving no information on the contribution of other cell types. The decrease in incorporation rate of the submandibular gland acinar cells is accompanied by a shift of polyribosomes towards monomers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219936
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