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  • 1
    ISSN: 1432-2307
    Keywords: Ultrastructure ; Morphometry ; Diabetic nephropathy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Morphological and morphometric studies of glomeruli were carried out in streptozotocin-induced diabetic rats using improved tissue processing and computerized morphometry. Increased mesangial matrix, occupying the enlarged diabetic mesangium, contained an abundance of dark granular material in addition to the microfibrils which were usually found in the control glomeruli. In the diabetic glomeruli, the lamina densa was thick and heterogeneous showing a dense layer both on its epithelial and endothelial aspects, and the lamina rara externa contained more fibrils than in control rats. Detailed estimation of the absolute values of the various compartments of the diabetic glomeruli by using perfusion-flxed materials and a computer-assisted digitizer revealed that the volume and surface area of the mesangium were increased more extensively than those of the capillary; the enlargement of the mesangial-capillary interface area was the most pronounced among the morphometric changes of the diabetic glomeruli; and that the moderate increase in capillary volume was associated with an increased radius. Our quantitative results showed that capillaries in the diabetic glomeruli had an extensively wider neck which may be the first sign of structural damage to the glomerular tuft.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2307
    Keywords: Podocyte ; Foot process ; Puromycin aminonucleoside ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ultrastructural changes in the podocytes were studied during the development of, and recovery from, acute puromycin aminonucleoside (PAN) nephrosis using high-resolution scanning electron microscopy (hrSEM) and transmission electron microscopy (TEM). In the process of development of PAN nephrosis, four types of early structural changes were observed before total loss of foot processes: formation of cytoplasmic blebs, masking of filtration clefts, flattening of foot processes, and retraction of foot processes. The masking of filtration clefts visualized by hrSEM corresponded to the multiplication of slit diaphragms and adhesion of foot processes in the TEM findings, and preceded retraction of the foot processes. Changes of podocyte configuration were produced. Recovery from this change of podocyte configuration began as islands of podocyte interdigitation, and was proceeded by expansion of the islands. During recovery, the primary processes were re-established either by retraction or perforation of the thin cytoplasm after the formation of foot processes. We conclude that loss of foot processes begins with the masking of filtration clefts. Recovery from the change in podocyte configuration begins with the formation of new foot processes.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-5604
    Keywords: Parathyroid hormone ; parathyroidectomy ; renal cortical brush border membrane vesicles ; sodium dependent phosphate transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Acute parathyroidectomy (PTX) is associated with an increase in phosphate (Pi) uptake by renal cortical brush border membrane (BBM). We investigated the response to acute and chronic PTX in the renal BBM. Kinetic studies of Pi uptake were carried out in 5 groups of rats as follows; control, acute PTX (1h), chronic PTX (20h and 72h), and chronic PTX (20h) treated with 10 IU of parathyroid hormone (PTH). The Na+-dependent Pi transport in BBMV was significantly increased 1h after PTX. However, this increase was not retained 72h after PTX. The Vmax of Pi uptake was significantly increased and the apparent Km was significantly decreased in acute PTX. In chronic PTX, the Vmax and the apparent Km returned to control leyels. The treatment with PTH increased the apparent Km and decreased Vmax significantly 20h after PTX. These results suggested an adaptive response to hyperphosphatemia in chronic PTX rats.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0878
    Keywords: Kidney ; Glomerulus ; Glomerular basement membrane ; Structural heterogeneity ; Scanning electron microscopy, high resolution ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the glomerular basement membrane (GBM) of the rat kidney was studied by means of high resolution scanning electron microscopy. Specimens were taken from kidneys perfused with paraformaldehyde, freeze-fractured and then processed with conductive staining. The fractured surface of glomerular tufts exhibited the inner and outer surface of the GBM uncovered by endothelial and epithelial cells. The lamina densa was composed of densely packed granular material together with scattered fibrils. The laminae rarae interna and externa were composed of a meshwork that showed some structural heterogeneities. The meshwork composing the lamina rara interna contained 5-to 9-nm-thick fibrils, had pores 11–30 nm wide, and was associated with granular material except in those places that corresponded with endothelial fenestrae. The meshwork of the lamina rara externa was made up of 6- to 11-nm-thick fibrils, and had smaller pores under the foot processes (10–24 nm wide) than those near the filtration slits (16–32 nm wide). In addition to the meshwork, the lamina rara interna contained microfibrils that were arranged differently depending on the topography of the capillary wall: scattered fibrils had no predominant orientation at the convex side, circumferential bundles lay at the concave side of the peripheral capillary wall, and had a circumferential arrangement in the paramesangial wall.
    Type of Medium: Electronic Resource
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