Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of mercury on renal lysosomal protein digestion was studied after administration of mercury in vitro and in vivo. Mercuric chloride or methylmercury chloride was added in vitro to lysosomal enzymes isolated from normal rats, and subsequently, digestion experiments were carried out using 125I-labeled lysozyme or cytochrome c as substrate proteins. Both mercury compounds produced a concentration-dependent inhibition of the degradation of the proteins, mercuric chloride being the strongest inhibitor. Mercuric chloride was also administered to rats in vivo for 5 to 8 months. Renal lysosomal enzymes from these animals also had a decreased ability to digest for the two substrate proteins. Furthermore, the digestion of lysozyme intravenously injected into mercury-intoxicated rats was decreased in renal cortical slices incubated in vitro. Electron microscope autoradiography showed that intravenously injected labeled lysozyme was located primarily over lysosomes in proximal tubule cells 1 hour after injection in both control animals and mercury-intoxicated rats. These results suggest a decreased catabolism of low molecular weight proteins in the kidney during chronic mercury intoxication.
 ...
PMID:Effects of mercury on lysosomal protein digestion in the kidney proximal tubule. 20 71

The effects of dextran on renal ultrastructure and on the handling of protein by renal proximal tubules were evaluated in dextran-tolerant rats. In vivo and in vitro systems were studied by a combination of electron microscope and cell fractionation techniques. Dextran was demonstrated by electron microscopy in endocytic vacuoles and lysosomes ing a dextran-retaining fixative, and there was an increase in the number and size of the lysosomes in the proximal tubule cells using a dextran-retaining fixative, and there was an increase in the number and size of the lysosomes in dextran-treated rats. A lysosomal accumulation of dextran was also demonstrated when 3H-dextran T-80 was injected i.v. and the renal cortex analyzed by tissue fractionation. When radioactive lysozyme was injected into dextran-treated rats, there was less filtration of the protein in the kidneys than there was in the controls, but the rate of degradation of the labeled protein in slices prepared from the renal cortex and incubated in vitro was the same in the two groups. Electron microscope autoradiography revealed that radioactive lysozyme reabsorbed by the tubule cells had a similar location in both control- and dextran-treated rats. It is concluded that lysosomal protein catabolism is not altered by the presence of dextran despite pronounced ultrastructural changes in the lysosomal system. The decreased filtration of labeled protein after dextran infusion is probably related to the decreased GFR during and immediately after the dextran infusion.
 ...
PMID:Effects of dextran on lysosomal ultrastructure and protein digestion in renal proximal tubule. 52 77

The ability of highly purified human leukocytic pyrogen (LP) to induce neutrophil lysosomal protein release is described. Human peripheral blood neutrophils isolated by Ficoll-Hypaque and dextran sedimentation were exposed to purified human LP. The specific granule-associated proteins, lysozyme and lactoferrin were selectively released, whereas primary granule (beta-glucuronidase) and cytoplasmic (lactic dehydrogenase) enzyme markers were not. Optimum release was observed after 45 min in the presence of Ca++ and Mg++. Cytochalasin B (5 microgram/ml) had no effect on LP-induced lysosomal enzyme release. Since the pyrogenicity of LP is dependent on prostaglandin synthesis, the effect of two potent inhibitors of prostaglandin synthesis on lysozyme release was studied. Both indomethacin and naproxen failed to inhibit specific granule protein release. These observations suggest that the concommitance of fever, elevated serum or urine lysozyme and hypoferremia may, in part, be explained by the interaction of LP and peripheral blood neutrophils.
 ...
PMID:Human leukocytic pyrogen induces release of specific granule contents from human neutrophils. 65 95

Separation of homogenates of human polymorphonuclear leukocytes (PMN) into different fractions by sedimentation in centrifugal fields that ranged from 126 x g to 50,000 x g resulted in a differential distribution of the lysosomal enzymes. Peroxidase, lysozyme, beta-glucuronidase, and acid phosphatase activity were separated from each other. This demonstrates that the lysosomes of human PMN comprise at least three and possibly four physically and chemically different cytoplasmic particles. Proteins which are more cationic than lysozyme and which may be analogous to cationic lysosomal protein of rabbit PMN were associated with lysozyme and beta-glucuronidase rich granules. Antibacterial activity was present in four of the five cell fractions which this work produced. These results are significant because they differ from those obtained with rabbits and because they directly influence future experimental design and interpretation, in attempts to analyze antibacterial, scavenging, and inflammatory capacities of human PMN. Since lysosomes differ physically, biochemically, and morphologically, they may well differ with respect to their function in the PMN.
 ...
PMID:Distribution of lysosomal enzymes, cationic proteins, and bactericidal substances in subcellular fractions of human polymorphonuclear leukocytes. 515 81

Low molecular weight dextran (Rheomacrodex) was infused into dextran resistant rats in a dose of 5 g/kg body weight. The kidneys were studied by electron microscopy at different time intervals after infusion using a special fixative for the demonstration of dextran. The lysosomes of proximal tubule cells gradually accumulated dextran which remained in small amounts even after 10 days. In separate kidney slice experiments the ability of dextran-loaded proximal tubule lysosomes to digest absorbed proteins was determined using 125I-labelled lysozyme. There were no changes in lysosomal protein digestion. Labelled dextran was resistant to digestion in vitro by homogenates of rat or rabbit kidney cortex or isolated rat lysosomal enzymes. It is concluded that the protein absorption pathway and lysosomal protein catabolism is unchanged after tubular uptake of dextran despite pronounced ultrastructural alterations to the lysosomal system and that dextran is resistant to lysosomal digestion in renal proximal tubules.
 ...
PMID:Dextran is resistant to lysosomal digestion in kidney tubules. 616 95

We have previously demonstrated that avian osteoclasts contain high levels of 17 beta-estradiol (17 beta E2) receptors and respond to 17 beta E2 treatment with a dose-dependent decrease in in vitro resorption of [3H] proline-labeled bone particles. To more accurately assess the influence of 17 beta E2 on osteoclastic activity, the specificity of estrogen modulation of resorption levels was determined using a quantitative pit resorption assay. Treatment with 17 beta E2 significantly decreased the number of osteoclast resorption pits formed compared with that after either vehicle or 17 alpha E2 treatment. Cotreatment with 17 beta E2 and hydroxytamoxifen (a complete 17 beta E2 antagonist in birds) abrogated the influence of 17 beta E2 on resorption activity. To elucidate the mechanism by which 17 beta E2 inhibits osteoclast activity, the effects of 17 beta E2 on the steady state mRNA levels of two avian osteoclast lysosomal proteins, lysozyme and a lysosomal membrane protein (LEP-100), were examined. Using highly purified avian osteoclasts, 17 beta E2 was shown to decrease lysosomal protein mRNA levels in a dose-dependent manner within 8 h of treatment in a process that required de novo protein synthesis. This response was specific for 17 beta E2, since the inactive stereoisomer 17 alpha E2 had no effect. Furthermore, coincubation of 17 beta E2 with hydroxytamoxifen eliminated the 17 beta E2 influence. After removal of 10(-8) M 17 beta E2, lysosomal gene mRNA levels returned to near-normal levels within 24 h. This is consistent with the previously reported ability of avian osteoclast-mediated resorption activity to recover from 17 beta E2 treatment. Lysozyme protein levels similarly decreased after 17 beta E2 treatment. These data suggest that avian osteoclasts are target cells for 17 beta E2 in vitro, that osteoclast activity in vivo is likely to be modulated by circulating levels of 17 beta E2, and that the 17 beta E2 inhibition of osteoclast resorption activity may be mediated at least in part via regulation of osteoclast lysosomal gene expression.
 ...
PMID:Estrogen modulation of avian osteoclast lysosomal gene expression. 844 Jan 93