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  • Ultrastructure  (4)
  • Engineering General  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Urological research 19 (1991), S. 319-322 
    ISSN: 1434-0879
    Keywords: Varicocele ; Rat, Histology ; Ultrastructure ; Temperature ; Infertility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary With no consistent animal prototype for the study of varicocele, we set out to create a model in the rat by complete ligation of the main branch of left spermatic vein (MBSV) or by partial ligation of the left renal vein. Three months later, the histology, ultrastructure and temperature of the testis and epididymis were studied. Microscopically, spermatogenic arrest was the most frequent anomaly seen. The most frequently noted ultrastructural change of the testis was distension of smooth endoplasmic reticula in Sertoli cells. The microvilli of columnar epithelia in epididymis were sparse and showed local defects. Lesions and increased temperatures in the testis and epididymis induced by the ligation of the left MBSV were similar to those seen in partial ligation of the left renal veins, with no significant differences between left and right. Significant differences were found, however, on comparison with the controls.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 94 (1997), S. 109-115 
    ISSN: 1432-0533
    Keywords: Key words Locus coeruleus ; Ultrastructure ; Dihydroetorphine ; Morphine ; Opioids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The locus coeruleus (LC) is a major noradrenergic nucleus in the brain. The activity of the LC neurons is chronically regulated by opioids. So far, very little is known about the morphological changes induced by chronic treatment with opioids. In the present study, the effects of chronic treatment with morphine and dihydroetorphine, a new narcotic analgesic with lower physical dependence potential than morphine, were investigated on the ultrastructure of the rat LC. Rats received saline or increasing doses of morphine or dihydroetorphine for 5 days by twice daily subcutaneous injections. Withdrawal was precipitated in half of the opioid-treated rats by a single intraperitoneal injection of naloxone 4 h after the last injections of opioids. The ultrastructure of the LC was examined by electron microscopy. Results showed that chronic morphine treatment induced a marked injury to the LC neurons. The primary changes in the cell body were the indentation of nuclei, the fragmentation and degranulation of rough endoplasmic reticulum, as well as the disaggregation of polyribosomes. Myelinoid bodies were seen in the processes. An accumulation of presynaptic vesicles was observed in some of the terminals which formed synaptic junctions with the LC neurons as compared to the normal controls. Naloxone-precipitated withdrawal from morphine did not stop the morphine-induced injury on the LC neurons except that less accumulation of presynaptic vesicles occurred. Chronic dihydroetorphine treatment only induced a slight change in the ultrastructure of the LC neurons. These results indicate that the LC neurons are more vulnerable to chronic treatment with morphine than to that with dihydroetorphine.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 291 (1997), S. 91-95 
    ISSN: 1432-0878
    Keywords: Key words ECL cells ; Omeprazole ; Granules/vesicles ; Ultrastructure ; Stomach ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The ECL cells are histamine- and peptide hormone-producing endocrine cells in the rat oxyntic mucosa. They are rich in secretory vesicles and also contain microvesicles and electron-dense granules. They operate under the control of circulating gastrin. In the present study, we examined the ECL-cell ultrastructure after long term treatment with omeprazole, which is known to induce hypergastrinemia, and after withdrawal of the drug. Rats received omeprazole (400 µmol/kg per day, orally) for 16 days and were killed 1, 5, 20, or 40 days after the last dose of the drug. Oxyntic mucosal specimens were processed for electron microscopy. Electron micrographs of ECL-cell profiles were analyzed planimetrically. The ECL-cell profile area increased promptly in response to omeprazole, the secretory vesicles and granules were reduced in number and volume density, the microvesicles were unchanged in number but reduced in volume density, and vacuoles appeared. Within a week after stopping the omeprazole treatment, the numbers and volume densities of secretory vesicles and microvesicles returned to pre-stimulation values. Also, the vacuoles disappeared promptly. The ECL-cell profile area decreased below the pre-stimulation level within five days after stopping treatment, while, in contrast, the granules increased in number and volume density. Somewhat surprisingly, the cell size and the granule compartment did not return to normal until 40 days after stopping treatment.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0878
    Keywords: Enterochromaffin-like cells ; Hypergastrinemia ; Hypertrophy ; Ultrastructure ; Omeprazole ; Portacaval shunt ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The histamine-producing enterochromaffinlike (ECL) cells in the acid-producing portion of the rat stomach responded to long-standing hypergastrinemia (omeprazole treatment daily for 8–10 weeks) with hypertrophy (and hyperplasia) and with a reduced number of granules and vesicles per unit cytoplasm. There was a reduction in the ratio of electron-dense granules versus vesicles and an increase in the profile diameter of the vesicles. Also, portacaval shunting (PCS) induced changes in the ECL cells, manifesting (i) as an increase in cell number and size, and (ii) as a reduced number of granules and vesicles per unit area. The cytoplasmic granules and vesicle profiles were enlarged, and the ratio of granules versus vesicles was reduced. The combination of PCS and long-standing hypergastrinemia (omeprazole treatment) produced a greatly enhanced ECL cell hypertrophy (and hyperplasia) and a marked reduction in the number of granules. The ratio of granules versus vesicles was markedly reduced while the profile diameters of both granules and vesicles were increased. The relative predominance of very large vesicles (vacuoles) was a prominent feature of the ECL cells in these rats.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 21 (1985), S. 1577-1581 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An efficient method for solving algebraic equations is given. The linear equations are solved only once and iterations are performed on the non linear equations. If an initial approximation to a desired root is available, then it is utilized in the solution process. Results of some computational experiments are given.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 30 (1990), S. 1233-1262 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The effect of the rotary inertia on the non-linear dynamics of plates that undergo a large reference displacement is examined in this paper. An assumed displacement field that accounts for the coupling between the stretching and bending of the plate as the result of considering the effect of the rotary inertia is used to identify the configuration of the plate. Furthermore, the coupling between the stretching and bending of the plate as the result of finite rotation is also considered in this investigation. Based on the assumed displacement field that accounts for the effect of the rotary inertia, a non-linear finite element formulation is developed for the large displacement analysis of plates. The element equations of motion are expressed in terms of a set of element invariants that depend on the assumed displacement field as well as the rotary inertia. The use of the formulation presented in this paper is demonstrated using numerical examples.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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