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  • 1
    ISSN: 1432-0509
    Keywords: Rectal carcinoma, CT ; Contrast media
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An attempt is made to establish the most appropriate examination procedure for staging rectal carcinoma by computed tomography (CT). Twentytwo patients with rectal carcinoma had CT performed preoperatively. The following three CT sequences were performed in all patients: a precontrast scan with 10-mm slices; a rapid sequence scan with 5-mm slices during bolus injection of contrast medium; and a postcontrast scan after a 10-min delay. Tumor extension and the presence of perirectal lymph nodes were evaluated separately and independently in all three CT sequences according to the TNM classification. All patients had surgical follow-up and the CT scans were compared to the surgical and histopathological findings. There was no significant difference in diagnostic outcome in the three CT procedures. Information obtained by frontal and lateral scout views were compared, and the lateral scout view proved more informative than the frontal scout view. For staging rectal carcinoma, narrow slice scanning and intravenous contrast media are superfluous and should be reserved for special cases. We recommend the use of lateral scout views.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 105 (1992), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The 12S oligomeric form of Staphylococcus aureusα-toxin has been studied with electron microscopy after incubation of the toxin with membrane preparations or liposomes. The target material originated from human platelet. Different electron microscopic preparation techniques were used including negative staining, freeze-fracture and vitrification in liquid ethane. Analysis of micrographs with image processing methods revealed two groups of ring-like structures corresponding to α-toxin oligomers. One form measured 75 Å in diameter and had a high stain density in the central protein deficient part while the other was larger with a diameter of 100 Å and less stain accumulation in the center. The conditions under which the latter were formed suggest that this corresponds to an inactive loosely-bound form of the toxin. The high stain density in the smaller particle is consistent with the presence of a penetrating pore in this structure.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2307
    Keywords: Atrophy ; Proximal tubule ; Human nephropathy ; Electron microscopy ; Quantitative changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Surgically removed perfusion-fixed human kidneys with chronic renal disease (hydronephrosis) were studied by electron microscopy in order to determine whether there is a quantitative relationship between ultrastructural changes in proximal tubules in atrophy and changes in the surrounding cortical interstitium. Morphometric techniques were applied to montages of electron micrographs each covering several tubular profiles in the cortical labyrinth and to montages representing cross-sections of individual proximal convoluted tubules at a higher magnification. In order to enable a quantification of the spatial relations between individual tubular cross-sections and adjacent peritubular capillaries a tubulo-capillary index (TCI) was defined. This index was based on the mean distances between individual tubular cross-sections and adjacent peritubular capillaries and on the fraction of tubular circumference facing capillaries. Normal tissue from similarly fixed human nephrectomy specimens, which had been removed mainly because of neoplastic disorders, served as control material. In the hydronephrotic kidneys the relative volume of cortical interstitium (excluding capillaries) covered a range from 19.2–70.3%. Inverse correlations were demonstrated between the relative volume of cortical interstitium and various structural variables of proximal convoluted tubules, including tubular wall volume, the volume of mitochondria and the surface area of basolateral membranes. The TCI showed positive correlations with these tubular variables. No significant correlation was found between the volume fractions of cortical interstitium and capillaries. Finally, it was found that an increase in the volume fraction of the cortical interstitium from 16.2% in controls to 24.7% in cortical areas of hydronephrotic kidneys was associated with a 40–50% reduction in the volume of mitochondria and in the surface area of basolateral membranes in proximal tubules. The results are consistent with a pathogenic interrelationship between tubular and interstitial changes. An important factor in this relationship might be disturbed topographic associations between tubules and blood capillaries caused by the increase in cortical interstitium. The results further show that even slight increases in the cortical interstitial volume are associated with significant quantitative changes in tubular fine structure suggesting impaired tubular functions.
    Type of Medium: Electronic Resource
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  • 5
    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.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1920
    Keywords: Computed tomography ; Contrast enhancement ; Fogging effect ; Completed stroke ; Cerebral infarct
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Information obtained from CT scan after contrast administration was evaluated in 59 consecutive stroke patients. CT scans before and after contrast administration were performed 3 days and 21/2 weeks after stroke. A plain CT scan was repeated 6 months later. Contrast enhancement was practically not seen on the first examination, but was seen in 46% on the second examination. There was a close relationship between the occurrence of contrast enhancement and the socalled “fogging effect”. Contrast scanning gave additional information only when this effect was present. Plain CT scans 3 days after stroke were superior to contrast scans taken at any time for detecting and visualizing cerebral infarcts.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 22 (1981), S. 61-65 
    ISSN: 1432-1920
    Keywords: Computed tomography ; Fogging effect ; Completed stroke ; Cerebral infarcts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fogging effect, whereby initially hypodense infarcts become isodense during the second and third week after the onset of stroke, was investigated in a prospective and consecutive series comprising 50 cases with completed stroke. CT scans were performed approximately 3 days, 10 days and 6 months after stroke. The fogging effect was found in 54% of cases. The hypodense areas reappeared on all scans at 6 months. Cerebral infarcts therefore may be overlooked or grossly underestimated if the scan is performed during the second and third week after stroke.
    Type of Medium: Electronic Resource
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