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  • 1
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  A three-step biotin-anti-biotin gold-detection system (method A) has been applied for ultraimmunocytochemistry using ultrasmall colloidal gold (0.8 nm) linked to anti-biotin antibodies which were visualized and enhanced by silver reduction. The reactivity for glucagon in human pancreatic islets and for cytochrome-c oxidase in heart mitochondria has been compared to a two-step ultrasmall immunogold technique (method B). For both antigens, method A provided significantly higher labelling indices (P〈0.001): the labelling density for cytochrome-c oxidase was 223/μm2 using method A and 78/μm2 using method B. For glucagon, the labelling density was 1455/μm2 with method A and 322/μm2 with method B. The results demonstrate that the silver-intensified biotin-anti-biotin gold-detection system is a valuable immunocytochemical method for signal enhancement. The method utilizes biotinylated antibodies from different species, allowing its broad application at the electron microscopic level.
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  • 2
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The mitochondrial DNA (mtDNA) of Japanese patients suffering from the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis and strokelike episodes (MELAS) exhibits a specific heteroplasmic A→G transition in the tRNALeu at position 3243. In this study, we investigated mtDNA from skeletal muscle, cardiac muscle, brain, liver, diaphragm, fibroblasts and blood cells of four Caucasians with MELAS, one younger healthy sister of two MELAS patients, and eleven controls. We found that 1) the mutation was present in all investigated tissues of Caucasians with MELAS but not in controls, 2) within a single patient, the tissue-specific variation of the copy number of mutated mtDNA covered the same range as in the skeletal muscle of different patients, 3) the mutation was also present in the blood cells of the healthy sister of two MELAS siblings.
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  • 3
    ISSN: 1432-1076
    Keywords: Cerebro-hepato-renal syndrome ; Plasmalogens ; Peroxisomes ; Zellweger syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have analyzed the phospholipid composition of various organs of patients with the cerebro-hepato-renal (Zellweger) syndrome. The phospholipid composition of tissues from controls and patients was very similar except for their plasmalogen contents. In controls about 50% of the phosphatidylethanolamine fraction of brain, heart, kidney and skeletal muscle and about 10% of that fraction in control liver tissue was found to consist of plasmalogen. In control heart muscle, but not in other control tissues about 25% of the phosphatidylcholine fraction consist of plasmalogens. In contrast, plasmalogens were nearly absent in the corresponding tissues of Zellweger patients. The amount of phosphatidylethanolamine plasmalogens in both erythrocytes and fibroblasts of Zellweger patients is lowered significantly compared to control erythrocytes and control fibroblasts respectively, although this reduction is not as dramatic as in brain, heart, kidney, skeletal muscle and liver of patients. Phosphatidylcholine-plasmalogens are only present in low amounts in both controls, heterozygotes and patients. In recent years considerable evidence has accumulated to show that peroxisomes are involved in cellular lipid metabolism. Notably, the key enzymes of ether lipid (plasmalogen) biosynthesis in rodents were recently found to be located in peroxisomes. Since electronmicroscopic studies have shown that peroxisomes are absent in liver and kidney of patients with the cerebro-hepato-renal syndrome, our results suggest that an inability to integrate these key enzymes in a functional peroxisome leads to a severe disturbance in plasmalogen biosynthesis. We propose that the multiple clinical and biochemical defects in Zellweger patients are secondary to a deficiency in peroxisomal function.
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  • 4
    ISSN: 1432-2307
    Keywords: Cerebro-hepato-renal (Zellweger-) syndrome ; Morphological diagnosis ; Ultrastructure ; Peroxisomes ; Autopsy ; Catalase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A female newborn, the second child of healthy non consanguineous parents, exhibited muscular hypotonia, areflexia, apathy, seizures, hepatomegaly and failure to thrive since birth. The peculiar skull shape was lacking. In the urine pipecolic acid and trihydroxycoprostanoic acid were excreted. At the age of seven weeks she died of bronchopneumonia. Lightmicroscopy revealed malformations and deficiency of myelinisation in the brain, renal cysts and fatty metamorphosis in the enlarged liver, which showed only minimal siderosis. Ultrastructurally no peroxisomes could be found in liver and kidney. No peroxisomes were detected by histochemical demonstration of catalase in frozen liver tissue which was taken immediately after death and stored for three months. Absence of peroxisomes is pathognomonic for the cerebro-hepato-renal syndrome of Zellweger and occurs in the liver irrespective of duration and degree of liver damage. It is best demonstrated by enzymehistochemical electron microscopy. With this method peroxisomes can be visualized even 30 h post mortem. In deep frozen normal liver tissue the activity of catalase remains very stable and enables the identification of peroxisomes even after a 12 months period of storage. In the cerebro-hepato-renal syndrome of Zellweger, frozen liver tissue should be stored for biochemical and diagnostic enzymehistochemical studies.
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  • 5
    ISSN: 1432-2307
    Keywords: Mitochondrial myopathy ; Cardiomyopathy ; Respiratory chain enzyme deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 5-month-old boy died of progressive heart failure that started at the age of 3 months. Autopsy revealed a mitochondrial cardiomyopathy and a mitochondrial myopathy of the limb muscle and diaphragm. Cytochemically random defects of cytochromec oxidase were visualized by light and electron microscopy in the diaphragm and especially the heart muscle, the limb muscle showing a diffuse attenuation whereas the liver and kidneys reacted normally. The activities of NADH-dehydrogenase (complex I) and cytochromec oxidase (complex IV) were severely diminished (20% residual activity of controls) in the skeletal and heart muscle. In the heart, succinate cytochromec reductase (complex II/III) was additionally decreased to the same degree. Loss of cytochromec oxidase activity was based on a reduction of both mitochondrial and nuclear derived subunits in the heart and diaphragm as revealed by immunohistochemical analysis, whereas the limb muscle showed a normal immunoreactive protein content. The results illustrate heterogeneous tissue expression of respiratory chain enzyme defects and demonstrate that a cardiomyopathy may be the leading presentation of a mitochondrial disorder in early infancy.
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  • 6
    ISSN: 1432-2307
    Keywords: Mitochondrial DNA ; Ageing ; Cytochrome c oxidase deficiency ; Extraocular muscles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Previous studies have revealed an increase of cytochrome c oxidase-deficient fibres/cells in the skeletal and heart muscle of humans during ageing. The enzyme defect is due to a lack of both mitochondrial and nuclear coded enzyme subunits. In the present investigation in situ hybridization of mitochondrial DNA (mtDNA) has been performed on extraocular muscles of humans over 70 years of age to show whether mutated mtDNA with the so called common deletion of 4,977 basepairs at position 8,482–13,460 of mtDNA accumulates in the cytochrome c oxidase-deficient fibres. The cytochrome c oxidase-deficient fibres revealed different hybridization patterns: a normal hybridization signal with three different mtDNA probes, a reduced or lacking signal with all three probes indicating depletion of mtDNA and a selective hybridization defect with the probe recognizing the “common deletion” region of mtDNA as evidence of mtDNA deletion. The results suggest that during ageing defects of cytochrome c oxidase are associated with different molecular alterations of mtDNA. Deletion and depletion of mtDNA are not the only nor probably the leading mechanisms responsible for the loss of respiratory chain capacity during ageing. The normal hybridization signal in most of the cytochrome c oxidase-deficient fibres and the loss of mitochondrial and nuclear protein subunits indicate the involvement of other, especially nuclear factors.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 432 (1998), S. 349-356 
    ISSN: 1432-2307
    Keywords: Key words Oncocytes ; Liver ; Cytochrome-c-oxidase ; Immunohistochemistry ; Respiratory chain defect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Oxyphilic hepatocytes, also called hepatic oncocytes, have been found in 20 of 47 cirrhotic livers (42%) with defects of the respiratory chain. Immunohistochemical studies using antisera against cytochrome-c-oxidase (complex IV) revealed respiratory chain-deficient oxyphilic foci in 16 of the 20 cases (75%). Fourteen percent of the oxyphilic areas were deficient, whereas only 8.5% of the nonoxyphilic liver nodules showed respiratory chain defects (P 〈 0.004). In addition, oxyphilic foci made up about 18% of all defective areas but were present in only 11.5% of the regenerative nodules. These results illustrate that oxyphilic cell change is associated with a higher propensity for the development of respiratory chain defects, but is not obligatory for this.
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  • 8
    ISSN: 1432-2307
    Keywords: Key words Cytochrome-c-oxidase ; Mitochondrial DNA ; In situ hybridization ; mtDNA polymerase gamma ; Human mitochondrial transcription factor A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Immunohistochemical studies were performed in 18 hyperfunctional parathyroids with oxyphil cell aggregates for the detection of cytochrome-c-oxidase (complex IV of the respiratory chain), mitochondrial DNA polymerase gamma and human mitochondrial transcription factor A (h-mtTFA). Seventy-three oxyphil areas exhibiting a defect of cytochrome-c-oxidase were found. The defect involved both the mitochondrially coded subunits II/III and the nuclear derived subunits Vab. There was no loss of mtDNA polymerase gamma or of h-mtTFA in these foci, corresponding to a high content of mtDNA revealed by in situ hybridization. Isolated defects of h-mtTFA were also not found. In contrast, isolated defects of mtDNA polymerase gamma were present in 22 oxyphil foci. These results show that defects of cytochrome-c-oxidase in oxyphil cells are not due to altered expression of h-mtTFA or DNA polymerase gamma, indicating that other nuclear factors involved in the generation of the respiratory chain may be impaired. The low incidence of defects of mtDNA polymerase gamma and the absence of alterations of h-mtTFA and cytochrome-c-oxidase in these foci suggest that defects of mtDNA polymerase gamma are of minor pathogenetic significance.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 436 (2000), S. 602-607 
    ISSN: 1432-2307
    Keywords: Key words Thyroid ; Hashimoto thyroiditis ; Oxyphil cell ; Immunohistochemistry ; bcl-2 ; Bax ; Fas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Immunoreactivity for bcl-2, Bax and Fas was analysed in 16 cases with Hashimoto thyroiditis. Bcl-2-expression was constantly seen in regular thyrocytes and in the mantle-zone of lymphofollicular infiltrates. However, thyrocytes in the vicinity of lymphoid infiltrates and, especially, mitochondria-rich oxyphil cells exhibited reduced staining or none at all for bcl-2. Bax was found to be weakly reactive or negative in normal thyrocytes and was not up-regulated in bcl-2-deficient epithelial cells. In contrast, expression of Fas was markedly increased both in typical thyrocytes and in oxyphil cells within areas of lymphocytic infiltration. In conclusion, focal lack of bcl-2 expression together with up-regulation of Fas is a constant feature of Hashimoto thyroiditis. The reaction pattern of oxyphil cells is identical to that of affected typical thyrocytes without proliferation of mitochondria. Loss of bcl-2 with up-regulation of Fas is therefore likely to precede oncocytic change. Whether these alterations are involved in the process of oncocytic transformation remains to be clarified, however.
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  • 10
    ISSN: 1432-2307
    Keywords: Progressive external ophthalmoplegia ; Mitochondrial myopathy ; Cytochrome-c-oxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In skeletal muscle biopsies of 8 patients with progressive external ophthalmoplegia combined light and fine structural cytochemical studies of cytochrome-c-oxidase revealed the absence of the enzyme in single fibres with or without accumulation of abnormal mitochondria. However, some fibres showed abnormal mitochondria without any deficiency of the enzyme. In one case with only slight mitochondrial proliferation the existence of the enzyme defect was the most remarkable finding. The occurence of the enzyme defect obviously does not depend on concominant structural alterations of the chondriom. The results are consistent with an acquired mitochondrial injury leading to a gradual loss of enzyme activity either earlier (with or without a minimal reactive mitochondrial proliferation) or later (after a phase of mitochondrial proliferation) in the course of the disease. Focal lack of cytochrome-c-oxidase activity is apparently a constant feature of the syndrome; it therefore may be not only of pathogenetic but also of diagnostic importance and in this connection cytochemical-fine-structural demonstration of cytochrome-c-oxidase is a valuable method. In contrast to the bio-chemical approach it allows not only the detection but also the exact anatomical localization of single fibre defects.
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