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  • 1
    Electronic Resource
    Electronic Resource
    The Importance of Microtubules in Determination of Shape and Intracellular Distribution of Peroxisomes (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 804 (1996), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1996.tb18660.x
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  • 2
    Electronic Resource
    Electronic Resource
    Nonradioactive in Situ Hybridization for Detection of mRNAs of Peroxisomal Enzymes in Rat Liver (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 804 (1996), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1996.tb18685.x
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  • 3
    Electronic Resource
    Electronic Resource
    Immunocytochemical investigation of catalase and peroxisomal lipid β-oxidation enzymes in human hepatocellular tumors and liver cirrhosis (1999)
    Springer
    Virchows Archiv 435 (1999), S. 486-495 
    Details
    ISSN: 1432-2307
    Keywords: Key words Peroxisomes ; Hepatocellular tumors ; Immunocytochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A significant reduction of catalase activity, a peroxisomal marker enzyme, occurs in human hepatic neoplasias, but no information is available on other peroxisomal proteins. We have studied by means of immunohistochemistry four specific proteins of peroxisomes (catalase and three enzymes of lipid β-oxidation) in human hepatocellular tumors of various differentiation grades from adenoma to anaplastic carcinoma. In all tumors, except the adenomas, the tumor cells contained fewer peroxisomes than extrafocal hepatocytes and the reduction of antigenic sites in the tumor types generally correlated with the degree of tumor dedifferentiation as assessed by classical histopathological criteria. Two poorly differentiated tumors had no detectable peroxisomes at all. There were no major differences in the intensities of the immunocytochemical staining for all four studied peroxisomal antigens in different tumors, suggesting that the neoplastic transformation affects the biogenesis of the entire organelle and not merely the individual peroxisomal enzyme proteins. Some tumors exhibited a distinct peripheral distribution of peroxisomes. In cases with associated liver cirrhosis, the hepatocytes in the adjacent liver showed marked peroxisome proliferation, forming large perinuclear aggregates, occupying occasionally the entire cytoplasm. Taken together, our observations indicate that peroxisomes are significantly altered in both hepatocellular tumors and liver cirrhosis and, thus, could be responsible for some of the metabolic derangements observed in those disease processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280050432
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  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructure of hepatocytes in golden ide (Leuciscus idus melanotus L.; Cyprinidae: Teleostei) during thermal adaptation (1987)
    Springer
    Anatomy and embryology 175 (1987), S. 303-313 
    Details
    ISSN: 1432-0568
    Keywords: Liver ultrastructure ; Temperature adaptation ; Fish ; Peroxisomes ; DAB Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphological alterations of hepatocytes of golden ide, Leuciscus idus melanotus, following adaptation to low and high temperatures (14 and 28°C) were investigated by means of light and electron microscopy. The temperature-dependent behaviour of peroxisomes was visualized cytochemically with the alkaline diaminobenzidine medium; the morphological studies were supplemented by the biochemical determination of catalase activity. Cold adaptation of ide hepatocytes is manifested by proliferation and stacking of endoplasmic reticulum, an enhanced secretory activity of Golgi fields and a higher number of peroxisomes as compared with the warmadapted animals. The latter organelles are characterized by a marked heterogeneity in size, shape and catalase activity, and by a more intimate association with mitochondria and endoplasmic reticulum. The occurrence of small peroxisomal profiles is restricted to lower temperature. Catalase activity can be shown both cytochemically and biochemically to increase during cold adaptation. Whereas the number of mitochondria seems to be unaffected by thermal adaptation, stacking of mitochondria as well as the formation of intramitochondrial membrane piles indicate cold-adaptive processes. A feature typical of warm-adaptation is the formation of membrane-glycogen complexes, which may represent the morphological expression of enhanced carbohydrate metabolism documented in a decreased storage of glycogen at 28°C. At 28°C lipid is the predominant storage product. These findings indicate that fish liver is well-suited to serve as a model for the analysis of the interaction of environmental temperature conditions and hepatic morphology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00309844
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  • 5
    Electronic Resource
    Electronic Resource
    The importance of tissue fixation for light microscopic immunohistochemical localization of peroxisomal proteins: the superiority of Carnoy's fixative over Baker's formalin and Bouin's solution (1995)
    Springer
    Histochemistry and cell biology 103 (1995), S. 187-195 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01454023
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  • 6
    Electronic Resource
    Electronic Resource
    Detection of mRNAs encoding peroxisomal proteins by non-radioactive in situ hybridization with digoxigenin-labelled cRNAs (1997)
    Springer
    Histochemistry and cell biology 108 (1997), S. 371-379 
    Details
    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
    URL: http://dx.doi.org/10.1007/s004180050178
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  • 7
    Electronic Resource
    Electronic Resource
    Differences in the response of Sprague-Dawley and Lewis rats to bezafibrate: The hypolipidemic effect and the induction of peroxisomal enzymes (1992)
    Springer
    Archives of toxicology 66 (1992), S. 327-333 
    Details
    ISSN: 1432-0738
    Keywords: Bezafibrate ; Rat ; Strain differences ; Lipids ; Marker enzymes ; Peroxisomes ; Mitochondria ; Micro-somes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of bezafibrate administered at 10 and 50 mg/kg/day for 7 days to male Sprague-Dawley (SD) and Lewis rats were investigated in order to determine the interrelation between the changes in serum and hepatic lipid contents and activities of selected peroxisomal, microsomal and mitochondrial enzymes in the two rat strains. In both strains, bezafibrate effectively reduced serum and hepatic lipids, increased the liver weight, induced a proliferation of peroxisomes, and selectively elevated the activities of carnitine acetyltransferase and of the enzymes of the peroxisomal Β-oxidation system. Moreover, immunoblotting revealed that the drug specifically enhanced the concentration of only those peroxisomal enzymes involved in fatty acid Β-oxidation. The data obtained demonstrate that although the responses initiated by bezafibrate are qualitatively similar in both strains, they differ in their magnitude in a dose-dependent manner, with the Lewis strain exhibiting a more pronounced response than the SD rats. These results show that dose-dependent strain differences as well as the generally known species differences should be taken into account in pharmacological and toxicological evaluations of fibrates in rodents. Furthermore, generalization and extrapolation from rodent studies should be treated with great caution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01973627
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  • 8
    Electronic Resource
    Electronic Resource
    Species differences in induction of hepatic enzymes by BM 17.0744, an activator of peroxisome proliferator-activated receptor alpha (PPARα) (1999)
    Springer
    Archives of toxicology 73 (1999), S. 440-450 
    Details
    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
    URL: http://dx.doi.org/10.1007/s002040050633
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  • 9
    Electronic Resource
    Electronic Resource
    Studies on secretory glycoproteins in the rat exocrine pancreas (1976)
    Springer
    Cell & tissue research 175 (1976), S. 227-243 
    Details
    ISSN: 1432-0878
    Keywords: Exocrine pancreas ; Golgi complex ; Glycoproteins ; Intracellular transport ; Secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using a double-label technique on isolated rat pancreatic lobules, the rate of synthesis and discharge of regular and fucosylated secretory proteins was studied under control conditions and after in vivo prestimulation with caerulein. Both labeled leucine and fucose were incorporated into pancreatic proteins at a linear rate, which was potentiated by in vivo stimulation. In pulse-chase experiments both regular and fucosylated secretory proteins were discharged into the medium in parallel. The in vivo pretreatment with caerulein caused an earlier discharge and increased the total amount released. Kinetic analysis of unstimulated (baseline) discharge of both classes of secretory proteins indicated a striking in vitro sensitivity by the previous in vivo treatment with caerulein. The biochemical data were compared to the fine structure of the Golgi complex under both control and prestimulated conditions. The Golgi stacks were composed of four to six individual cisternae which in some cases were connected by intercisternal pores. Transporting vesicles were observed fusing along the total length of the outermost cisterna on both the cis- and transside and with the lateral ends of the intermediate cisternae. Under control conditions only the last trans-cisterna contained some electron opaque material; in vivo prestimulation led to distension and filling of all cisternae in an individual Golgi-unit. Numerous stages of transformation of the last transcisterna into condensing vacuoles were observed, lending support to the hypothesis that during packaging of secretory products the membranes of the Golgi complex undergo a continuous turnover.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232080
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrastructural, immunocytochemical and morphometric characterization of liver peroxisomes in gray mullet, Mugil cephalus (1999)
    Springer
    Cell & tissue research 297 (1999), S. 493-502 
    Details
    ISSN: 1432-0878
    Keywords: Key words Liver peroxisomes ; Catalase ; Palmitoyl-CoA oxidase ; DAB cytochemistry ; Morphometry ; Immunochemical methods ; Mugil cephalus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Peroxisomes of the hepatocytes of gray mullets, Mugil cephalus, were characterized cytochemically and immunocytochemically using antibodies against the peroxisomal proteins catalase and palmitoyl-coenzyme A (CoA) oxidase. In addition, morphometric parameters of peroxisomes were investigated depending on the hepatic zonation, the age of the animals and the sampling season. Mullet liver peroxisomes were reactive for diaminobenzidine, but presented a marked heterogeneity in staining intensity. Most of the peroxisomes were spherical or oval in shape, although irregular forms were also observed. Their size was heterogeneous, with profile diameters ranging from 0.2 to 3 µm. Peroxisomes tended to occur in clusters, usually near the mitochondria and lipid droplets. They also showed a very close topographical relationship to the smooth endoplasmic reticulum. Mullet liver peroxisomes did not contain cores or nucleoids as rodent liver peroxisomes, but internal substructures were observed in the matrix, consisting of small tubules about 60 nm in diameter and larger semicircles 120 nm in diameter. The volume density of peroxisomes was higher in periportal hepatocytes of mullets sampled in summer than in pericentral hepatocytes, indicating that mullet peroxisomes vary depending on physiological and environmental conditions. By immunoblotting, the mammalian antibodies cross-react with the corresponding proteins in whole homogenates of mullet liver. Paraffin sections immunostained with the antibodies against catalase and palmitoyl-CoA oxidase showed a positive reaction corresponding to peroxisomes localized in the hepatocyte cytoplasm. In agreement, the ultrastructural study revealed that catalase and palmitoyl-CoA oxidase are exclusively localized in the peroxisomal matrix in fish hepatocytes, showing a dense gold labeling. The presence of the peroxisomal β-oxidation enzyme palmitoyl-CoA oxidase in peroxisomes indicated that these organelles play a key role in the lipid metabolism of fish liver.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051376
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