Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.11.1.7 (peroxidase)
 65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Exocrine acinar cells possess two cytochemically distinct populations of secondary lysosomes. One population is Golgi associated and has demonstrable acid phosphatase (AcPase) activity, whereas the second is basally located and lacks AcPase activity but has trimetaphosphatase (TMPase) activity. The basal lysosomes are tubular in shape and rapidly label with horseradish peroxidase (HRP) after intravenous injection. In the present study using isolated rat parotid acinar cells, the two lysosomal populations were separated by cell fractionation on Percoll density gradients and were analyzed biochemically and by EM cytochemistry. On 35% Percoll gradients, two peaks of AcPase and beta-hexosaminidase, both lysosomal marker enzymes, and succinic dehydrogenase, an enzyme marker for mitochondria, could be resolved. The major peaks of beta-hexosaminidase and succinic dehydrogenase and the minor peak of AcPase corresponded with the dense lysosome fraction. The major peak of AcPase and the minor peaks for beta-hexosaminidase and succinic dehydrogenase coincided with the light membrane fraction. Galactosyl transferase (a marker enzyme for Golgi saccules) and 5'-nucleotidase (a plasma membrane marker) were also associated with this fraction. By electron microscopy, the light membrane fraction was seen to contain tubular elements, multivesicular bodies (MVB), Golgi saccules, GERL, immature secretory granules, and some mitochondria. Electron microscopic cytochemical examination showed that these tubular structures were lysosomes. The dense lysosome fraction contained lysosomes positive for both AcPase and TMPase. After continuous incubation of isolated acinar cells with HRP, reaction product was rapidly localized to the light membrane fraction (greater than 2 min), where it was found in vesicles and tubular lysosomes. By 10 min it was present in MVB and tubular lysosomes, but by 60 min no HRP reaction product had appeared in the dense lysosomes. These results demonstrate that the tubular lysosomes are separable from dense lysosomes, typical secondary lysosomes, and are involved in the initial stages of endocytosis.
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PMID:Density gradient separation of two populations of lysosomes from rat parotid acinar cells. 255 1

In the neonatal mouse the mandibular condyle serves as an important growth center for the developing mandible. The youngest cells in this organ are the chondroprogenitor cells that are the source for new differentiating chondroblasts. The present study provides new data concerning the fine structure and cytochemical characteristics of the cartilage precursor cells as seen in suckling mice. The condylar chondroprogenitor cells normally reveal a mesenchyme-like appearance with multiple, elongated cell processes that enable close contact between neighboring cells. These cells also exhibit a variety of pinocytotic vesicles, coated pits and appear to be actively involved in the internalization of a fluid-phase marker horseradish peroxidase. Further, the progenitor cells were found to contain trimetaphosphatase reaction products within lysosomal bodies and alkaline phosphatase reactivity along their plasma membrane. Precipitates of calcium complexes in the form of calcium pyroantimonate could be demonstrated in association with the plasmalemma of the cells as well as with the extracellular collagen fibrils. Matrix granules, representing cartilage proteoglycans, became a distinct feature following staining with ruthenium red and were found to be in close contact with the extracellular collagen fibrils and with the plasmalemma. Hence, in addition to their active role in cell proliferation, the progenitor cells are also involved in the synthesis and secretion of major extracellular macromolecules such as collagen and proteoglycans.
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PMID:Further characterization of the chondroprogenitor zone in mandibular condyles of suckling mice. An ultrastructural and cytochemical study. 282 27

Rat molar gingiva was studied by tracer experiments employing horseradish peroxidase and by cytochemical demonstration of inorganic trimetaphosphatase. Though non-keratinized junctional epithelium appeared to have no effective diffusion barrier against the permeation of peroxidase, keratinized sulcular epithelium had an evident barrier for the tracer at the junction between the granular and cornified layers. The barrier to peroxidase permeation was closely associated with the presence of either numerous membrane-coating granules or a cornified layer. The basal cells of both junctional and sulcular epithelia frequently took up peroxidase by means of coated pits, vesicles and endocytotic vacuoles. Inorganic trimetaphosphatase activity was present in dense bodies, multivesicular bodies and vacuoles, but not necessarily related closely to peroxidase incorporation within the cytoplasm.
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PMID:Peroxidase penetration in the crevicular epithelium of rat molar gingiva. 301 Sep 17

The ultrastructure and cytochemistry of eosinophils from adult fowl and ducks with either spontaneous or experimentally induced eosinophilia were examined. The results showed that a high proportion of the eosinophils in the peripheral blood of eosinophilic birds had ultrastructural features different from those of normal eosinophils. In both species, there was a reduction in cell size. Fowl eosinophil granules showed similar morphological changes to those seen in the quail with many crescentic and vacuolated forms being present. In eosinophilic ducks, the crystalline interna of the specific granules were often fragmented or were either partially or completely lysed. Cytochemically, peroxidase activity in both species was generally unaltered in abnormal eosinophils compared with those from normal birds. This correlates with the findings in man. However, amounts of acid phosphatase and trimetaphosphatase were reduced in many cells, with a large proportion of granules being non-reactive. The latter observation corresponds with that in quail but differs from man, in which stimulated eosinophils have increased enzymatic activity.
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PMID:Fine structural and cytochemical studies of eosinophils from fowls and ducks with eosinophilia. 302 59

Normal eosinophil development in the Japanese quail (Coturnix coturnix japonica) was similar to that described in the fowl and the duck, with granulogenesis occurring in the Golgi apparatus. The characteristic lipid droplets were small in the immature eosinophils, and after staining specifically for lipid, small moieties were also traced to the Golgi apparatus. In mature eosinophils the lipid droplets measured between 1.0 and 1.5 micron in diameter and they were surrounded by profiles of smooth endoplasmic reticulum. Eosinophilia was difficult to induce in quails; injections of either horse serum or bovine serum albumin (BSA)/aluminium hydroxide produced a poor response. In some quails in which eosinophilia was produced, however, eosinophil granules showed many crescentic and vacuolated forms. The lipid droplets in the activated eosinophils were fused in many cells to form large intracellular aggregates of lipid. Quail eosinophils, which hitherto have been regarded as peroxidase-negative, had strong activity in the lipid droplets of cells from stimulated birds. It is postulated that this peroxidase-positive reaction may represent a form of ceroid or lipofuscin pigment resulting from lipid peroxidation. Acid phosphatase and trimetaphosphatase reactions were reduced in many activated cells, with a large proportion of granules being non-reactive. The results of dietary manipulations in quails appear to suggest that in stressful situations the eosinophil metabolism is altered and there is a reduction in the number of lipid droplets in the cell.
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PMID:Ultrastructural and cytochemical studies in normal Japanese quail (Coturnix coturnix japonica) eosinophils and in those from birds with experimentally induced eosinophilia. 302 60

Administration of the antimicrotubular agent colchicine to adult rats (0.5 mg/100 g of body weight for 6 hr) induces formation of extended aggregates of tubular, vesicular, and cisternal organelles in the absorptive cells of the small intestine. The phosphatase reaction pattern (thiamine pyrophosphatase, acid phosphatase, acid trimetaphosphatase) suggests that the majority of them belongs to the lysosomal system (Ellinger and Pavelka, 1984). The present study extends these findings and examines the uptake and fate of intravenously injected horseradish peroxidase (HRP) at the basal and lateral cell surfaces and of intraluminally applied HRP at the apical cell surface. HRP, applied to control animals and animals pretreated with colchicine, was internalized at both apical and basolateral cell surfaces of the absorptive cells, and delivered into endosome-like vesicles, multivesiculated bodies (mvbs), dense bodies (dbs), and in several instances into Golgi cisternae. Following intraluminal application, evidence was obtained for the transport of HRP across the cell; in contrast, intravenously applied HRP was never detected at the apical cell surface. Colchicine pretreatment did not stop the uptake of HRP, which was rapidly sequestered to the clustered tubules, vesicles, and cisternae, as well as to the mvbs and dbs. After longer intervals, the portion of HRP-reactive tubules, vesicles, and cisternae within the clusters increased: 60 min after HRP-administration all of them contained HRP-activity. These results indicate that the colchicine-induced clustered organelles are recipients of endocytic materials internalized at the apical as well as at the basolateral cell surface.
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PMID:Colchicine-induced tubular, vesicular and cisternal organelle aggregates in absorptive cells of the small intestine of the rat. II.--Endocytosis studies. 303 16

The internalization of cationized ferritin (CF) was studied in isolated pancreatic acinar cells in vitro. Horseradish peroxidase (HRP) was used in conjunction with CF to compare internalization of soluble-phase and membrane-bound tracers. The mode of internalization of CF was dependent upon tracer concentration and origin of the plasma membrane (apical vs. lateral-basal). At the lower tracer concentrations (0.19 and 0.38 mg/ml), internalization from the apical cell surface occurred via small vesicles. The tracer then appeared in multivesicular bodies, in tubules, and in irregular membrane-bound structures. After 15 min, CF particles were seen in many small vesicles near the Golgi apparatus, but not in the Golgi saccules. In contrast, at the lateral-basal cell surface the CF particles tended to form clusters. These clusters were more pronounced at higher CF concentrations (0.76 and 1.5 mg/ml) and were associated with elongated cellular processes, which seemed to engulf CF accumulations in a phagocytic manner. Once internalized, CF was found primarily in large irregular structures which appeared to migrate slowly toward the nucleus, reaching a juxtanuclear position after approximately 30 min. CF was observed in lysosomes after 30-45 min and by 90 min most of the CF was confined to large vacuoles and to trimetaphosphatase-positive lysosomes. Similar routes were observed when cells were double-labeled with CF and HRP, where endocytic structures showed co-localization of both tracers. The results of this study indicate the importance of the Golgi region in the intracellular sorting of internalized apical membrane. Furthermore, this work confirms the presence of distinct endocytic pathways at the apical and lateral-basal cell surfaces.
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PMID:Internalization of cationized ferritin by isolated pancreatic acinar cells. 394 55

The maturation and distribution of the endocytotic apparatus in outside cells of cleavage-stage mouse embryos have been studied to determine the nature and sequence of changes associated with the differentiation of the polarized trophectoderm epithelium of the blastocyst. Various quantitative and qualitative techniques used at the light and electron microscopic levels have revealed an incremental pattern of endocytotic maturation and polarization. Oocytes, eggs and blastomeres within embryos up to the early 8-cell stage contain clusters of prelysosomal endocytotic vesicles (endosomes) distributed randomly in the cortical cytoplasm. During the 8-cell stage and continuing into the early 16-cell stage, endosomes become progressively localized in the apical cytoplasm beneath the microvillous pole. Endosome polarization is initiated prior to overt polarization of the surface membrane. Concomitant with endosome polarization, pinocytotic activity at the cell surface, revealed by horseradish peroxidase labelling, becomes segregated preferentially to the apical rather than the basolateral membrane. The final maturation phase occurs at the late 16-cell stage when secondary lysosomes, characterized by trimetaphosphatase reactivity, form and polarize in the basal cytoplasm.
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PMID:Maturation and polarization of the endocytotic system in outside blastomeres during mouse preimplantation development. 409 47

In parotid acinar cells, horseradish peroxidase (HRP) administered via the main excretory duct is endocytosed from the apical cell surface in smooth C- or ring-shaped vesicles (Oliver, C. and A. R. Hand. 1979. J. Cell Biol. 76:207). These vesicles ultimately fuse with lysosomes adjacent to the Golgi apparatus. The present investigation extends these findings and examines the uptake and fate of intravenously injected HRP from the lateral and basal cell surfaces of resting and stimulated parotid and pancreatic acinar cells from rats and mice. Isoproterenol and pilocarpine were used to stimulate the parotid gland and the pancreas, respectively. HRP was internalized in smooth and coated vesicles primarily in areas of membrane infoldings. Both the number of coated vesicles and the amount of tracer internalized increased markedly following secretagogue administration. In both resting and stimulated cells, the HRP was rapidly sequestered in a unique system of basally located lysosomes that possess trimetaphosphatase activity, but not acid phosphatase activity. At 1-3 h after HRP administration, reaction product was also found in multivesicular bodies, vesicles, and lysosomes adjacent to the Golgi apparatus. With time, more HRP was localized in Golgi-associated lysosomes. By 6-7 h, tubules in the apical cytoplasm of stimulated cells contained HRP reaction product. When native ferritin was administered retrogradely and HRP injected intravenously, both tracers could be localized in the same lysosome after 4-5 h, indicating that material taken in from all cell surfaces mixes in Golgi-associated lysosomes. The results of this study suggest that two separate and distinct endocytic pathways exist in exocrine acinar cells: one involves membrane retrieval from the apical cell surface; and the other is a stimulation-dependent process at the lateral and basal cell surfaces.
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PMID:Endocytic pathways at the lateral and basal cell surfaces of exocrine acinar cells. 714 84

Eosinophils and neutrophils are granulocytic leukocytes that are present in the blood of most vertebrates. Studies have been performed on lower vertebrates to understand the biological roles of the cells in defense mechanisms and to establish phylogenetic studies and new experimental models. Whether these 2 cell types exist in reptiles is a matter of controversy. In the blood of turtles there are 2 types of granulocytes that exhibit eosinophilia, one of them with round cytoplasmic granules and the other with elongated cytoplasmic granules. It has been suggested that these cells may be eosinophils in different stages of maturation but they also may be distinct cell types, i.e. eosinophils and neutrophils. In the present study, we characterized the 2 types of granulocytes that are present in the blood of Chrysemys dorbignih, using cytochemical techniques. Type I eosinophils showed activity of nonspecific esterase, peroxidase activity that is resistant to KCN, and basic proteins. Type II eosinophils exhibited activity of trimetaphosphatase, alkaline phosphatase, nonspecific esterase, peroxidase that is sensitive to KCN, and basic proteins. These observations indicate the existence of 2 distinct cell types in the blood of Chrysemys dorbignih, type I and type II eosinophils, that correspond to eosinophils and heterophils (neutrophils) of mammals and other vertebrates.
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PMID:Cytochemical characterization of eosinophilic leukocytes circulating in the blood of the turtle (Chrysemys dorbignih). 1266 93


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