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  • 1
    ISSN: 1420-9071
    Keywords: Stress-response proteins ; heat shock proteins ; hyperosmolality ; human tumor cells ; MCF-7 ; HeLa S3 ; immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Exposing cells to adverse conditions usually elicits expression of stress-response (heat shock) proteins (srp). Here we show that hyperosmolar growth conditions do not uniformly affect srp expression in MCF-7 and HeLa S3 cells, derived from carcinoma of the breast and cervix, respectively. Thus, whereas srp 27 expression was increased in MCF-7, but not in HeLa S3, the opposite was the case with srp 72. On the other hand, hyperosmolality did not induce αB-crystallin or ubiquitin in either cell line. These findings show that srp expression by the human tumor cells studied is non-coordinate, suggesting that each srp is independently modulated.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Dihydroxyacetone ; ATP-sensitive K+ channels ; GK rat ; glycerol phosphate shuttle ; pancreatic beta cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the GK (Goto-Kakizaki) rat, a genetic model of non-insulin-dependent diabetes mellitus, glucose-induced insulin secretion is selectively impaired. In addition, it has been suggested by previous studies that impaired glucose metabolism in beta cells of the GK rat results in insufficient closure of ATP-sensitive K+ channels (KATP channels) and a consequent decrease in depolarization, leading to a decreased insulin release. We have recently reported that the site of disturbed glucose metabolism is probably located in the early stages of glycolysis or in the glycerol phosphate shuttle. In the present study, in order to identify the impaired metabolic step in diabetic beta cells, we have investigated insulin secretory capacity by stimulation with dihydroxyacetone (DHA), which is known to be directly converted to DHA-phosphate and to preferentially enter the glycerol phosphate shuttle. In addition, using the patch-clamp technique, we also have studied the sensitivity of DHA on the KATP channels of beta cells in GK rats. The insulin secretion in response to 5 mmol/l DHA with 2.8 mmol/l glucose was impaired, and DHA sensitivity of the KATP channels was reduced in beta cells of GK rats. From these results, we suggest that the intracellular site responsible for impaired glucose metabolism in pancreatic beta cells of GK rats is located in the glycerol phosphate shuttle.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Key words Dihydroxyacetone ; ATP-sensitive K+ channels ; GK rat ; glycerol phosphate shuttle ; pancreatic beta cell.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the GK (Goto-Kakizaki) rat, a genetic model of non-insulin-dependent diabetes mellitus, glucose-induced insulin secretion is selectively impaired. In addition, it has been suggested by previous studies that impaired glucose metabolism in beta cells of the GK rat results in insufficient closure of ATP-sensitive K+ channels (KATP channels) and a consequent decrease in depolarization, leading to a decreased insulin release. We have recently reported that the site of disturbed glucose metabolism is probably located in the early stages of glycolysis or in the glycerol phosphate shuttle. In the present study, in order to identify the impaired metabolic step in diabetic beta cells, we have investigated insulin secretory capacity by stimulation with dihydroxyacetone (DHA), which is known to be directly converted to DHA-phosphate and to preferentially enter the glycerol phosphate shuttle. In addition, using the patch-clamp technique, we also have studied the sensitivity of DHA on the KATP channels of beta cells in GK rats. The insulin secretion in response to 5 mmol/l DHA with 2.8 mmol/l glucose was impaired, and DHA sensitivity of the KATP channels was reduced in beta cells of GK rats. From these results, we suggest that the intracellular site responsible for impaired glucose metabolism in pancreatic beta cells of GK rats is located in the glycerol phosphate shuttle. [Diabetologia (1994) 37: 1082–1087]
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0428
    Keywords: Glucagon ; insulin ; somatostatin ; streptozotocin ; sympathetic nerve ; diabetic rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Changes in glucagon, insulin and somatostatin secretion induced by electrical splanchnic nerve stimulation were examined in rats treated with streptozotocin as neonates and as adults. In order to study the direct neural effects we used the isolated perfused rat pancreas with intact left splanchnic nerve in vitro. In normal rats splanchnic nerve stimulation causes significant decreases in insulin (30–40%) and somatostatin (30–50%) secretion at both 16.7 mmol/l and 1 mmol/l glucose concentrations. In the neonatal streptozotocin-diabetic rats splanchnic nerve stimulation at 16.7 mmol/l glucose decreased insulin secretion (14%) further than in the control rats (30%), however, somatostatin secretion did not decrease to the same extent. Similar results were also observed at the low (1 mmol/l) glucose concentration. On the other hand, percent decreases of insulin and somatostatin secretion induced by splanchnic nerve stimulation in the streptozotocin-diabetic rats were similar to the values observed in the normal control rats. The glucagon secretion in response to splanchnic nerve stimulation at 16.7 mmol/l glucose from pancreatic Alpha cells in both types of induced diabetes is exaggerated, and the degree of exaggeration seems to parallel the severity of the hyperglycaemia. However, the splanchnic nerve stimulation-induced glucagon secretion at 1 mmol/l glucose was impaired in the streptozotocin-diabetic rats, but not in the neonatal streptozotocin-diabetic rats. These data suggest that the sensitivity of diabetic Alpha and Delta cells to sympathetic neural activation are blunted, whereas the sensitivity of Beta cells is enhanced in the diabetic animal model.
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  • 5
    ISSN: 1432-0533
    Keywords: Olivopontocerbellar atrophy ; Argyrophilic inclusion ; Pontine nucleus ; Ubiquitin ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Patients with olivopontocerebellar atrophy (OPCA) were studied, and cytoplasmic inclusions were observed in some of the remaining neurons of the pontine nuclei, nuclei reticularis tegmenti pontis and arcuate nuclei. The cytoplasmic argyrophilic inclusions were demonstrated by silver impregnation techniques such as Bielschowsky and Bodian staining. With hematoxylin and eosin stain, the inclusions were sharply demarcated and appeared pale. The inclusions were not stained by the following routine histological methods: Klüver-Barrera, phosphotungstic acid hematoxylin, Holzer, periodic acid-Schiff, Mallory azan, alcian blue, nile blue, Masson trichrome, Congo red, thioflavine S, oil red O and Sudan black B stains. Immunohistochemistry with anti-ubiquitin antiserum showed that these inclusions were ubiquitinated. However, the inclusions did not react with any of the following antibodies (Abs) or antisera: anti-phosphorylated neurofilament (NF) Ab, anti-nonphosphorylated NF Abs (160 and 200 kDa), anti-paired helical filament antiserum, anti-tau antiserum, anti-tubulin Abs (alpha and beta), anti-microtubule-associated proteins antiserum, anti-glial fibrillary acidic protein antiserum, anti-vimentin Ab, anti-desmin Ab, anti-cytokeratin Abs (low and high molecular weights), anti-actin antiserum, anti-skeletal myosin antiserum and anti-myelin basic protein Ab. Ultrastructurally, the inclusion bodies noted in OPCA were composed primarily of fibrils having a width ranging from about 24 to 40 nm, which were entirely coated with osmiophilic granular material along their whole length. They were occasionally intermingled with a few filaments about 10 nm in width. Electron microscopical examination on silver-impregnated specimens revealed that each granule-coated fibril had a great affinity for silver particles. In elucidating the pathogenesis of OPCA, it was considered to be an important neuropathological finding that some of the remaining pontine neurons affected by OPCA developed characteristic cytoplasmic argyrophilic inclusions.
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  • 6
    ISSN: 1432-0533
    Keywords: Olivopontocerebellar atrophy ; Oligodendroglia ; Argyrophilic inclusion ; Ubiquitin ; Leu-7
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We described cytoplasmic inclusions in glial cells in 18 patients with olivopontocerebellar atrophy (OPCA) (multiple system atrophy, MSA). These glial inclusions showed intense argyrophilia with modified Bielschowsky's and Bodian's silver impregnation techniques, and were observed in the pons, cerebellar white matter, midbrain, medulla oblongata and basal ganglia, as well as cerebral white matter and spinal cord. None of the 54 control cases had glial argyrophilic inclusions. Immunohistochemically, these inclusions were intensely labeled by anti-ubiquitin antibody. Some of them reacted with an antibody to Rosenthal fiber (RF) protein. The cytoplasm of ubiquitinated inclusion-bearing glial cells was immunostained by anti-Leu-7 antibody, but not by anti-GFAP antibody. Ultrastructurally, the glial inclusions were composed primarily of approximately 24- to 40-nm fibrils, which were coated with osmiophilic granular material along their length in longitudinal section. These fibrils appeared as annuli in cross section. Often, a central granule approximately 5 nm in diameter was seen in the lucent lumen of a cross-sectioned fibril. The granule-coated fibrils were not seen in the glial filament-containing astrocytes. Electron microscopic examination of silver-impregnated specimens revealed that the granule-coated fibrils had strong affinity for silver. Immunoelectron microscopy using the indirect immunoperoxidase techniques with antibodies to ubiquitin and RF protein revealed that the electron-dense reaction products respective to both were located on constituents of glial inclusions. Our observation that Leu-7-positive glial cells, mainly oligodendroglial cells, had argyrophilic ubiquitinated inclusions may be of significance for the evaluation of the pathology of OPCA(MSA).
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  • 7
    ISSN: 1432-0533
    Keywords: Creutzfeldt-Jakob disease ; Ballooned neurons ; Ultrastructure ; αB-Crystallin ; Stress-response proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This report concerns ultrastructural and immunohistochemical studies on ballooned neurons of ten patients with Creutzfeldt-Jakob disease (CJD). While abundant ballooned neurons and severe white matter degeneration was seen in six Japanese cases, only occasional ballooned neurons and no white matter degeneration was observed in four cases from the files of Montefiore Medical Center. Ultrastructurally, the ballooned neurons contained granule-coated fibrils of 25 to 40 nm in width and 10-nm neurofilaments. The immunohistochemical studies revealed that most ballooned neurons expressed αB-crystallin, with deposits of reaction products observed in the cytoplasm. A similar intracellular staining pattern was also seen with the antibody to phosphorylated neurofilament proteins (pNFP). Although the proportion of stained ballooned neurons was less, a positive reaction was also observed with antibodies against ubiquitin, stress-response protein 27 (srp 27) and synptophysin, but not with an antibody to srp 72. Our findings suggest that expression of pNFP and synaptophysin by ballooned neurons may reflect axonal impairment and that the presence of αB-crystallin, srp 27 and ubiquitin may be related to the degenerative processes that neurons undergo in CJD.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0533
    Keywords: Spinal cord neurofibrillary tangles ; Parkinsonism-dementia complex on Guam ; Guamanian amyotrophic lateral sclerosis ; Ultrastructure ; Immunoelectron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The immunohistochemical and ultrastructural characteristics of spinal cord neurofibrillary tangles (NFTs) were examined in Guamanian amyotrophic lateral sclerosis and in parkinisonism-dementia complex on Guam. The spinal cord NFTs reacted with antibodies to tau protein (tau-2), ubiqitin and paired helical filaments (PHFs). Ultrastructurally, the components of the NFTs were seen as randomly arranged fibrils which were often associated with osmiophilic granules; small bundle-like arrangements were also occasionally observed. Individual NFT fibrils appeared as straight fibrils with a diameter of approximately 15 nm and constricted fibrils with a periodicity of approximately 80 nm. Ultrastructural microscopic examination of specimens stained by the modified Bielschowsky method and with the antibodies revealed silver particles and the products of the tau, ubiquitin and PHF immunoreactions on the NFT fibrils. This is the first demonstration of the fine structure of the spinal cord NFTs.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0533
    Keywords: Astrocytic inclusion ; S-100 protein ; Microtubule-associated protein 1B ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Immunohistochemical studies were carried out on the new type of cerebral cortical astrocytic inclusions recently discovered in a 20-year-old patient with maldeveloped brain and micropolygyria. The inclusions appeared as eosinophilic structures (hematoxylin and eosin stain) and did not exhibit argyrophilia (modified Bielschowsky method). The inclusions were strongly stained by the antibody against S-100 protein (S 100) and to a lesser extent by the antibody to microtubule-associated protein 1B (MAP 1B). In contrast to Rosenthal fibers, the astrocytic inclusions did not react with antibodies to αB-crystallin, glial fibrillary acidic protein and ubiquitin. No positive reactions were obtained with antibodies against heat-shock protein 27 (HSP 27), HSP 72, actin, vimentin, desmin, cytokeratin, myelin basic protein, β-tubulin, MAP 2, tau protein, paired helical filament, phosphorylated neurofilament protein (NFP), nonphosphorylated NFP, synaptophysin, cathepsin D, α1-antichymotrypsin, α1-antitrypsin and basic fibroblast growth factor. By immunoelectron microscopy, the products of the reaction with the anti-S 100 antibody appeared as heterogeneous granular deposits and with the antibody to MAP 1B they were randomly scattered throughout the astrocytic inclusions. Our results demonstrate that the immunohistochemical profile of the recently described inclusions differs from that of Rosenthal fibers. Whether the novel inclusions are involved in congenital astrocyte dysfunction and cerebral malformation remains to be established.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0533
    Keywords: Astrocyte ; Glia limitans ; Gliosis ; Hemidesmosome ; Anchorage density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electron microscopical examination of devastated and reticular gliosis-replaced areas of two human brains revealed novel anchorage densities (ADs) associated with hemidesmosome-like structures (HDLSs) in perivascular astrocytes; the densities, 200–300 nm away from the cell membrane overlying the basal lamina, ran parallel to the membrane. The subplasmalemmal ADs usually received fibrils from the main stream of the deeply located glial fibrils, and sent isolated 13- to 16-nm fibrils roughly perpendicularly to the unusually prominent and frequently continuous HDLSs on the inner leaflet of the cell membrane, undercoated by a thickened basal lamina. The variable profiles of the ADs indicated that they were cell membrane-connected sheets or meshes that were virtually completely composed of bundles of glial fibrils intercrossing at variable angles or running roughly parallel to one another. All these findings suggest that the ADs may provide a significant support to the cell membrane facing the perivascular space.
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