Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Keywords: ENDOTHELIAL-CELLS ; MODEL ; GENE-EXPRESSION ; MICE ; ESCHERICHIA-COLI ; EPITHELIAL-CELLS ; HEMOLYTIC-UREMIC SYNDROME ; ANGIOTENSIN-II ; P38 MAP KINASE ; CHRONIC KIDNEY-DISEASE
    Abstract: BACKGROUND/AIMS: Shiga toxin 2 may trigger classical hemolytic uremic syndrome (HUS) eventually leading to renal failure. Klotho, a transmembrane protein, protease and hormone mainly expressed in kidney is involved in the regulation of renal phosphate excretion and also retains renal protective effects. Renal failure is associated with renal depletion of klotho. The present study explored the influence of Shiga toxin 2 on renal klotho expression. METHODS: Mice were injected with either solvent or Shiga toxin 2 and urinary flow rate and phosphate excretion were determined in metabolic cages. Renal transcript levels were measured by quantitative RT-PCR and renal protein abundance by Western blotting. Plasma concentrations of 1,25(OH)2D3 and FGF23 were determined by ELISA and plasma phosphate and urea concentrations by photometry. RESULTS: Shiga toxin 2 treatment was followed by increase of plasma urea concentration, urinary flow rate and renal phosphate excretion but not of plasma phosphate concentration. Shiga toxin 2 treatment strongly decreased klotho mRNA expression and klotho protein abundance in renal tissue. Shiga toxin 2 treatment further increased tumor necrosis factor (Tnfalpha) mRNA levels, as well as protein abundance of phosphorylated p38 MAPK in renal tissue. The treatment significantly increased renal Cyp27b1 and decreased renal Cyp24a1 mRNA levels without significantly altering plasma 1,25(OH)2D3 levels. Shiga toxin 2 treatment was further followed by increase of plasma FGF23 concentrations. CONCLUSION: Shiga toxin 2 treatment stimulated Tnfalpha transcription, down-regulated renal klotho expression and increased FGF23 formation, effects presumably contributing to renal tissue injury.
    Type of Publication: Journal article published
    PubMed ID: 25471359
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    Keywords: PATHWAY ; NF-KAPPA-B ; SKELETAL-MUSCLE ; MYOCARDIAL-INFARCTION ; ANGIOTENSIN-II ; TGF-BETA ; EPITHELIAL-MESENCHYMAL TRANSITION ; RENAL FIBROSIS ; CHRONIC KIDNEY-DISEASE ; TAK1
    Abstract: BACKGROUND: AMP-activated protein kinase (Ampk) is a sensor of the cellular energy status and a powerful regulator of metabolism. Activation of Ampk was previously shown to participate in monocyte-to-fibroblast transition and matrix protein production in renal tissue. Thus, the present study explored whether the catalytic Ampkalpha1 isoform participates in the regulation of the renal fibrotic response following unilateral ureteral obstruction (UUO). METHODS: UUO was induced in gene-targeted mice lacking functional Ampkalpha1 (Ampkalpha1-/-) and in corresponding wild-type mice (Ampkalpha1+/+). In the obstructed kidney and, for comparison, in the non-obstructed control kidney, quantitative RT-PCR, Western blotting and immunostaining were employed to determine transcript levels and protein abundance, respectively. RESULTS: In Ampkalpha1+/+ mice, UUO significantly up-regulated the protein abundance of the Ampkalpha1 isoform, but significantly down-regulated the Ampkalpha2 isoform in renal tissue. Phosphorylated Ampkalpha protein levels were significantly increased in obstructed kidney tissue of Ampkalpha1+/+ mice but not of Ampkalpha1-/- mice. Renal expression of alpha-smooth muscle actin was increased following UUO, an effect again less pronounced in Ampkalpha1-/- mice than in Ampkalpha1+/+ mice. Histological analysis did not reveal a profound effect of Ampkalpha1 deficiency on collagen 1 protein deposition. UUO significantly increased phosphorylated and total Tgf-ss-activated kinase 1 (Tak1) protein, as well as transcript levels of Tak1-downstream targets c-Fos, Il6, Pai1 and Snai1 in Ampkalpha1+/+ mice, effects again significantly ameliorated in Ampkalpha1-/- mice. Moreover, Ampkalpha1 deficiency inhibited the UUO-induced mRNA expression of Cd206, a marker of M2 macrophages and of Cxcl16, a pro-fibrotic chemokine associated with myeloid fibroblast formation. The effects of Ampkalpha1 deficiency during UUO were, however, paralleled by increased tubular injury and apoptosis. CONCLUSIONS: Renal obstruction induces an isoform shift from Ampkalpha2 towards Ampkalpha1, which contributes to the signaling involved in cell survival and fibrosis.
    Type of Publication: Journal article published
    PubMed ID: 26285014
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0302-4598
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-0738
    Keywords: Key words BM 17.0744 ; β-Oxidation pathway ; Peroxisomes ; Peroxisome proliferators ; Species differences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract BM 17.0744, a new anti-diabetic and lipid-lowering agent, leads also to strong hepatomegaly and carnitine acetyl transferase (CAT) increase in the liver of rats, a phenomenon known from fibrates. For information on the relevance of changes in liver of rats to other species, we investigated the effects of BM 17.0744 on lipids and selected marker enzymes related to β-oxidation in rats, dogs and guinea-pigs, so-called high and low responders to peroxisome proliferators. To examine selectivity other enzymes were also determined, e.g. esterase, urate oxidase (UOX) and cytochrome c oxidase (CYT.C.OX.). Lowering of triglycerides and cholesterol in blood serum and/or liver was observed in pharmacological dose range in the three species tested. In dogs and guinea-pigs, liver and kidney weights were unaffected even in dogs in medium and high dose groups with high systemic exposure and severe toxicity. In male Sprague-Dawley rats treatment with 1.5, 3, 6 and 12.5 mg/kg per day BM 17.0744 selectively elevated the activities of CAT and acyl-CoA oxidase (AOX) by ≤200 and 20-fold, respectively. Administration of BM 17.0744 to Beagle dogs (1.5, 4, 12 mg/kg per day) and guinea-pigs (3 and 12 mg/kg per day) enhanced the activities of CAT and AOX dose-dependently by a factor of two to three only. Immunoblotting revealed a drug-specific enhancement of the amount of β-oxidation enzymes in rats, which is in accord with the rapid and coordinated transcriptional activation shown in Northern dot blot analysis. Nuclear run-on assays demostrated a real transcriptional activation. BM 17.0744 activates peroxisome proliferator-activated receptor α (PPARα), which could be shown by transactivation assays. The stimulation of PPARα by BM 17.0744 was stronger than that of the known ligands WY 14.643 and ETYA. Activation of PPARγ can be excluded. Taken collectively, the data demonstrate an enhancement of the β-oxidation system by BM 17.0744 paralleled by lipid-lowering in all species investigated. The activation of the nuclear factor PPARα may explain the changes in liver and the metabolic effects on the molecular level. The lack of an increase in liver and kidney weights and the relatively moderate enhancement of activities of β-oxidation-related enzymes in dogs and guinea-pigs indicate that the excessive response observed in rats is not applicable to other, predominantly non-rodent, species. On the basis of these data and the experience with fibrates a specific risk for humans is not expected.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have compared the effects of fixation with three commonly used fixatives upon preservation of the antigenicity of six peroxisomal proteins in rat liver using both immunohistochemical staining and Western blotting of fixed tissue extracts. The immunoreactivity of all six peroxisomal proteins was well preserved and peroxisomes were clearly identified in material fixed in Carnoy's fixative. Moreover, the corresponding proteins stained well in Western blots prepared from extracts of Carnoyfixed material. The intensity of the immunohistochemical staining was reduced at different rates for individual peroxisomal proteins after fixation in Baker's formalin, but peroxisomes were still well visualized with antibodies to catalase and some β-oxidation enzymes. No evidence of immunohistochemical staining for any peroxisomal antigens was obtained after fixation in Bouin's fluid. For detection of the antibody binding sites in Carnoy's fixed material, the avidin-biotin-peroxidase complex (ABC) with aminoethyl carbazole as chromogen was found to be superior to the methods of peroxidase-antiperoxidase/diaminobenzidine and protein A-gold with silver intensification. Using Carnoy-fixative and the ABC-method, we demonstrate light microscopic immunohistochemical localization of peroxisomal antigens in several rat tissues as well as in human post-mortem liver.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The immunogold labeling technique has been extremely useful in investigation of the structure and function of peroxisomes. In this report a few examples of the application of this technique with significant implications in the field are briefly reviewd. The problem of extra-peroxisomal catalase, the subject of long controversy between the biochemists and cytochemists, was settled with the immunogold technique, which unequivocally revealed the presence of that enzyme not only in the cytoplasm, but also in the euchromatin region of nucleus, in addition to peroxisomes. On the other hand, lactate dehydrogenase, a typical cytoplasmic protein, has also been shown recently to be present in peroxisomes and to be involved in the reoxidation of NADH produced by the peroxisomal β-oxidation system. The immunogold technique has revealed several distinct compartments in the matrix of mammalian peroxisomes: urate oxidase in the crystalline cores, α-hydroxy acid oxidase B in the marginal plates andd-amino acid oxidase in a non-crystaline condensed region of matrix. The specific alterations of peroxisomal proteins are reflected in their immunolabeling density with gold particles. Quantitation of gold-label by automatic image analysis has revealed that the induction of lipid β-oxidation enzyme proteins by diverse hypolipidemic drugs is initiated and more pronounced in the pericentral region of the liver lobule. Finally, immunogold labeling with an antibody to 70 kDa peroxisomal membrane protein has identified a novel class of small peroxisomes that initially incorporate radioactive amino acids more efficiently than regular peroxisomes and thus may represent early stages in the biogenesis of peroxisomes.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  We have used a non-radioactive in situ hybridization (ISH) protocol for the detection of mRNAs encoding proteins localized in peroxisomes. In this presentation the literature on detection of ”peroxisomal mRNAs” is reviewed and the results obtained by application of the non-radioactive method are compared with those obtained by hybridization with radioactive probes. Moreover, the special processing conditions and the application of the method for the specific visualization of mRNAs coding for several peroxisomal proteins with different abundance levels and distinct tissue distributions are presented. The combination of the following technical details in the ISH procedure were found to be essential for obtaining optimal sensitivity and good histological quality of the preparations: (a) perfusion-fixation with a fixative containing 4% depolymerized paraformaldehyde/0.05% glutaraldehyde, (b) the use of paraffin embedding instead of frozen sections, (c) specific proteinase K-digestion time for each tissue, and (d) the use of digoxigenin-labelled cRNA probes (hydrolyzed to a length of about 200 bases) for detection. By using this technique, we were able to localize several peroxisome-specific mRNAs with different degrees of abundance: (1) high-level (catalase and urate oxidase) and (2) low-level (all β-oxidation enzymes and the 70-kDa peroxisomal membrane protein) in rat liver and kidney. The specificity of the method was confirmed by the negative results obtained with corresponding sense controls and the distinct positive staining patterns obtained for albumin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNAs. All transcripts for mRNAs encoding peroxisomal proteins were localized to the cytoplasm of hepatocytes, with all nuclei as well as epithelial cells of bile ducts and sinusoidal cells remaining negative. In rat kidney, the catalase transcripts were confined to proximal tubular epithelial cells, which is consistent with the high abundance of peroxisomes in this part of the nephron. In contrast, no transcripts for urate oxidase were present in the kidney, corresponding to the absence of that protein in this organ. The transcripts for GAPDH on the other hand were localized in proximal and distal tubular epithelial cells as well as in collecting ducts. The application of this technique to the rat adrenal gland and testis in recent unpublished studies have revealed exclusive localization of catalase transcripts to the adrenal cortex and to interstitial cells of Leydig, which are known to be rich in microperoxisomes. These observations demonstrate the suitability of this technique for accurate localization of mRNAs encoding peroxisomal proteins and for the analysis of alterations in the expression of the corresponding genes under different experimental conditions.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Peroxisomes of the digestive glands of mussels, Mytilus galloprovincialis Lmk, were investigated by immunoblotting and immunohistochemistry using rabbit antibodies against several mammalian hepatic peroxisomal proteins. Western blot analysis of main subcellular fractions revealed immunoreactive polypeptides with molecular weights comparable to those of the corresponding mammalian hepatic proteins. They could be localized to the peroxisomal matrix in the case of catalase, multifunctional enzyme (PH), and palmitoyl-CoA oxidase (AOX), and to the peroxisomal membrane in respect to PMP 70. The purification of peroxisomes by metrizamide density gradient centrifugation revealed the existence of two subpopulations with densities of 1.16 and 1.20 g cm–3 exhibiting different protein compositions. In paraffin sections, positive immunolabeling for catalase was distributed along the apical cytoplasm of the epithelia of digestive ducts and stomach and throughout the cytoplasm of digestive tubule cells. The peroxisomal β-oxidation enzymes, AOX and PH, also appeared predominantly in the ducts and the stomach epithelia with a weaker immunolabeling in the tubules. At the electron microscopic level a clear labeling with gold particles was observed in the peroxisomal matrix with the anti-guinea pig catalase antibody. In addition to peroxisomes, the anti-PH antibody also labeled the mitochondria. The similarity in the protein composition of molluscan and mammalian peroxisomes as revealed by the present study indicates that those proteins have been well conserved in evolution suggesting that functionally peroxisomes in molluscs could also be involved in the metabolism of lipids and in detoxification of xenobiotics. Thus, the antibodies tested could provide useful tools for detection of peroxisomal induction in molluscan biomonitoring programs for the assessment of aquatic environmental pollution.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The substrate specificity and the intraperoxisomal localization of α-hydroxyacid oxidase in rat liver has been investigated cytochemically by the cerium technique and biochemically with a luminometric assay. Rat liver is fixed by perfusion with a low concentration (0.25%) of glutaraldehyde and vibratome sections are incubated for 60 min at 37°C in a medium containing 3 mM CeCl3, 100 mM NaN3 and 5 mM of an α-hydroxyacid in 0.1M of one of the following buffers: Pipes, Mops, Na-cacodylate,Tris-maleate, all adjusted to pH 7.8. Ten different α-hydroxyacids with a chain length between 2 and 8 carbon atoms were tested. The best results were obtained with glycolic, argininic andl-α-isocaproic acids. These cytochemical findings were confirmed also biochemically using purified peroxisomal fractions isolated by gradient centrifugation in metrizamide. The pattern of the intraperoxisomal localization of the enzyme was influenced markedly by the type of buffer used for the cytochemical incubation. Whereas in theTris-maleate medium both the cores and the matrix stained with the same intensity, with all other buffers the reaction in cores was more prominent. The staining of cores was abolished by pretreating sections inTris-maleate (pH 7.8) or alkaline pyrophosphate buffers. These observations establish the substrate specificity of α-hydroxyacid oxidase in rat liver and demonstrate the delicate association of this enzyme with the crystalline cores and the matrix of peroxisomes in rat liver.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The immunogold labeling technique has been extremely useful in investigation of the structure and function of peroxisomes. In this report a few examples of the application of this technique with significant implications in the field are briefly reviewed. The problem of extraperoxisomal catalase, the subject of long controversy between the biochemists and cytochemists, was settled with the immunogold technique, which unequivocally revealed the presence of that enzyme not only in the cytoplasm, but also in the euchromatin region of nucleus, in addition to peroxisomes. On the other hand, lactate dehydrogenase, a typical cytoplasmic protein, has also been shown recently to be present in peroxisomes and to be involved in the reoxidation of NADH produced by the peroxisomal β-oxidation system. The immunogold technique has revealed several distinct compartments in the matrix of mammalian peroxisomes: urate oxidase in the crystalline cores, α-hydroxy acid oxidase B in the marginal plates and d-amino acid oxidase in a non-crystaline condensed region of matrix. The specific alterations of peroxisomal proteins are reflected in their immunolabeling density with gold particles. Quantitation of gold-label by automatic image analysis has revealed that the induction of lipid β-oxidation enzyme proteins by diverse hypolipidemic drugs is initiated and more pronounced in the pericentral region of the liver lobule. Finally, immunogold labeling with an antibody to 70 kDa peroxisomal membrane protein has identified a novel class of small peroxisomes that initially incorporate radioactive amino acids more efficiently than regular peroxisomes and thus may represent early stages in the biogenesis of peroxisomes.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...