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

The propagation of immune-responsive cells in vitro has provided the basis for substantial contributions to our understanding of many aspects of the mammalian immune response. In contrast, the potential for exploring the innate immune response of insects using cultured cells is only beginning to be developed, particularly with various mosquito cell lines from the genera Aedes and Anopheles. Immune-reactive mosquito cell lines express various defensive factors, including transferrin, lysozyme, cecropin, defensin, and prophenoloxidase activities. In this review, we discuss insect immunity in the context of key concepts that have emerged in the study of the mammalian immune system, with emphasis on the properties of the cells that participate in the immune response. The nature of established cell lines and their contributions to our understanding of immune functions in humans and insects is described, with emphasis on our own work with the C7-10 and Aag-2 mosquito cell lines from Aedes albopictus and Aedes aegypti, respectively. Finally, we offer some speculation on further advances in insect immunology that may be facilitated by work with cells in culture.
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PMID:Exploration of mosquito immunity using cells in culture. 1116 96

Local immunity is analyzed in 81 patients (146 eyes) aged 16-49 years with three clinical patterns of keratocone. During long remission, IgG level was the maximum. In progressive disease, sIgA and transferrin levels were increased. The most pronounced shifts were detected in the patients with acute keratocone: increased concentrations of IgM, C3 and C4 complement components, alpha 1-antitrypsin, orosomucoid, lysozyme activity, and immune complexes. These data prompt the development of pathogenetically based approaches to the treatment of patients with various clinical immunological types of keratocone.
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PMID:[Characterization of immunological parameters of the lacrimal fluid in patients with various types of the course of keratoconus]. 1156 75

The integumental defenses provide a physical and chemical barrier to the attachment and penetration of microbes. Besides the entrapping and sloughing of microbes in the mucus, the latter contains many antibacterial substances including anti-bacterial peptides, lysozyme, lectins and proteases. The gastro-intestinal tract is a hostile environment of acids, bile salts and enzymes able to inactivate and digest many viruses and bacteria. In most cases the integumental defenses are sufficient to protect against even quite virulent organisms which often only produce disease when the integument has been physically damaged. If a microbe gains access to the tissues of the fish, it is met with an array of soluble and cellular defenses. The complement system, present in the blood plasma, plays a central role in recognising bacteria and its activated products may lyse the bacterial cells, initiate inflammation, induce the influx of phagocytes and enhance their phagocytic activity. Complement can be activated directly by bacterial products and constituents and also indirectly by other factors, principally C-reactive protein and lectins, which can also bind to the bacterial surface. Plasma also contains a number of factors which inhibit bacterial growth(e.g. transferrin and anti-proteases) or which are bactericidal e.g. lysozyme. Following the infection of fish with virus pathogens, infected cells produce interferon. This induces antiviral defenses in neighbouring cells which are then protected from becoming infected. Anti-viral cytotoxic cells are able to lyse virally infected cells and thus reduce the rate of multiplication of virus within them. Innate defenses thus provide a pre-existing and fast-acting system of protection which is non-specific and relatively temperature-independent and thus has several advantages over the slow-acting and temperature-dependent specific immune responses.
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PMID:Innate host defense mechanisms of fish against viruses and bacteria. 1160 98

The iron-binding glycoprotein human lactoferrin (hLF) is involved in the host defense against infection and is a modulator of inflammatory reactions. We generated monoclonal antibodies (mAbs) to hLF as tools to assist both structure-function studies and the development of recombinant human lactoferrin for applications in human health care. Binding experiments with ten distinct anti-hLF mAbs to tryptic and recombinant hLF fragments in ELISA and/or on immunoblots revealed that five mAbs bound to conformational epitopes residing in the N-lobe (residues 1 to 334), whereas the other five bound to C-lobe conformational epitopes (residues 335 to 692). None of the mAbs bound to hLF denatured upon reduction. Monoclonal antibody E11 appeared to bind to the arginine-rich N-terminus of hLF, which is the binding site for heparin, bacterial lipopolysaccharide, human lysozyme, DNA and receptors. The dissociation constant of the distinct mAbs for hLF ranged from 0.5 to 18 nM, without differences in affinity for unsaturated or iron-saturated hLF, indicating that the conformational changes subject to incorporation of iron do not seem to affect the exposure and/or conformation of the antibody epitopes. The mAbs did not bind to human transferrin, a protein closely related to hLF in size, primary amino acid sequence and structure. Two C-lobe specific mAbs, E2 and E8, cross-reacted with bovine and/or porcine lactoferrin, indicating that human, bovine and porcine lactoferrin share antigenic determinants. This panel of mAbs will be used to develop quantitative and qualitative immunoassays for hLF and to delineate which regions of hLF are relevant to its anti-infective and anti-inflammatory properties.
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PMID:Characterization of monoclonal antibodies against human lactoferrin. 1216 35

Urinary proteins from 14 patients with tubulointerstitial nephritis were analyzed by cellulose acetate membrane electrophoresis. Urinary total protein concentrations were measured, and urinary 15 proteins (prealbumin, albumin, alpha(1)-microglobulin, alpha(1)-antitrypsin, alpha(2)-macroglobulin, haptoglobin, retinol binding protein, transferrin, beta(2)-microglobulin, IgA, IgG, kappa- and lambda-light chains, cystatin C, and lysozyme) were identified by the use of a rapid and highly sensitive colloidal silver staining reagent suited for use with cellulose acetate membranes, as reported previously by Matsuda et al. (J Clin Lab Anal 15:171-174, 2001; Clin Chem47:763-766, 2001) and Hiratsuka et al. (J Clin Lab Anal 10:403-406, 1996). We also analyzed urinary total protein concentration and urinary protein fractions according to the presence of acute or nonacute interstitial nephritis. In addition, the relationship between urinary protein fraction and complications of interstitial nephritis was analyzed. The goal of this work was to find a useful index for the diagnosis of tubulointerstitial nephritis.
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PMID:Cellulose acetate membrane electrophoresis in the analysis of urinary proteins in patients with tubulointerstitial nephritis. 1264 Jun 26

Using molecular approaches, we have recently shown that the C7-10 mosquito cell line from Aedes albopictus, and the Aag-2 line from Aedes aegypti, secrete a variety of immune peptides into the culture medium, including cecropins, defensins, transferrin, and lysozyme. The diversity of these peptides makes it difficult to quantify the relative activities of each molecule, because possible synergistic interactions may occur. Using a microtiter plate assay with live bacteria, we now show that C7-10 cells secrete an activity that is more potent against the Gram-positive bacterium, Micrococcus luteus, than against Gram-negative Escherichia coli. This lysozyme-like activity is accompanied by production of a lytic zone in an agarose plate assay containing commercially available, lyophilized M. luteus. Properties of the lysozyme-like activity from C7-10 cells included a broad pH optimum from 5.5 to 6.5, and heat-sensitivity above 42 degrees C. Amounts of secreted activity increased during the initial 24h of incubation with heat-killed bacteria. During this induction, lysozyme-like activity was found primarily in the cell culture supernatant.
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PMID:Detection of lysozyme-like enzymatic activity secreted by an immune-responsive mosquito cell line. 1267 52

As a potential tool for proteomics and protein characterization, in-gel cysteine- and arginine-specific cleavage is demonstrated by means of trypsin or endoproteinase Lys-C for six model proteins (lysozyme, alpha-lactalbumin, beta-lactoglobulin, ribonuclease A, albumin, and transferrin), ranging in size from 14 kDa to 79 kDa. Chemical modifications of cysteine (aminoethylation with bromoethylamine or N-(iodoethyl)-trifluoroacetamide, and subsequent guanidination) and lysine (acetylation) prior to tryptic digestion releases peptides delineated by cysteine or arginine residues. Peptide products are analyzed by MALDI-TOF-MS, ESI-MS, and ESI- and MALDI-MS/MS (with a quadrupole time-of-flight instrument). Complications induced by acrylamide alkylations of cysteines were avoided by substituting lower pH bis-tris polyacrylamide gels for tris-glycine. Sequence coverages from 35 to 86% were obtained and amino acid compositions of generated peptides could be confirmed by comprehensive y- and b-ion series. Detailed information about, in particular, cysteine rich proteins after gel electrophoresis were obtained. The chemistries for modification and cleavage specificities at cysteine residues provide an alternative means to characterize and identify proteins separated by gel electrophoresis.
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PMID:In-gel derivatization of proteins for cysteine-specific cleavages and their analysis by mass spectrometry. 1271 30

The aim of this study was to explore the antimicrobial activity of human follicular fluid (HFF), to test the hypothesis that different strains of the same bacterial species could display different patterns of susceptibility to antimicrobial action of HFF, and to preliminarily investigate the possible mechanism of antimicrobial action of this fluid. Antimicrobial activity of 60 samples of HFF toward 30 Streptococcus agalactiae strains was determined by the agar diffusion method and broth dilution method. To explore the mechanism of antimicrobial activity, biochemical analyses were performed with selected fluid samples. The obtained results indicate that 38.3% fluid samples did not inhibit bacterial growth, 53.3% showed moderate and 8.3% high antimicrobial activity. The tested effect of HFF on S. agalactiae strains was bactericidal and was not strain dependent. Lysozyme activity was detected in HFF exhibiting antimicrobial activity. There were no statistically significant differences in concentrations of estradiol, progesterone, transferrin, iron, total protein and albumin levels among tested samples regardless of the different rate of antimicrobial activity. The obtained results indicate that lysozyme is most probably a crucial antibacterial agent in this fluid; however, some other still unidentified factors may contribute to it.
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PMID:Antimicrobial activity of human follicular fluids. 1455 60

Ticks host obligate intracellular bacteria that range from benign symbiotes to virulent human pathogens. The effects on those bacteria of antimicrobial peptides (AMPs) involved in arthropod innate immunity to microbial infections are largely unknown. We evaluated effects of AMPs and a c-type lysozyme on host cell-free suspensions of the tick symbiotes Rickettsia monacensis and Rickettsia peacockii with stain-based infectivity and viability assays. Cecropin A at a concentration of 8 muM: had a lethal effect on both rickettsiae while ceratotoxin A was approximately 20-fold less effective. Toxicity of both AMPs was synergized by lysozyme, an enzyme expressed by ticks. Lactoferrin, a transferrin, had no effect on R. monacensis at up to 110 microM. The rickettsiae were less sensitive to the AMPs than is typical of bacteria that grow extracellularly. Our assays may be useful in the study of AMP activity against other obligate intracellular bacteria.
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PMID:Susceptibility of Rickettsia monacensis and Rickettsia peacockii to Cecropin A, Ceratotoxin A, and lysozyme. 1613 58

Serum bacteriostasis of Staphylococcus aureus was characterized quantitatively and quantitatively. Bacteriostasis was proportional to the concentration of serum. Reproducibility was good; freezing and thawing did not materially affect the end point. Four of six different strains, including the propagating S. aureus strain for phage 73 which does not produce coagulase, were susceptible to serum bacteriostasis in similar titers; two were not susceptible at all. All six strains were effective inhibitors of bacteriostasis. Active and inactive coagulase were also inhibitors. In contrast to sensitive S. aureus, S. epidermidis and Streptococcus salivarius were not uniformly susceptible to bacteriostasis by different serums. Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Salmonella montevideo, S. zymogenes, and Diplococcus pneumoniae were not susceptible. Among gram-positive bacteria, only D. pneumoniae inhibited S. aureus bacteriostasis. Agglutinins of S. aureus and nonspecific substances such as lysozyme, beta-lysin, C-reactive protein, and transferrin were not responsible for S. aureus serum bacteriostasis. After diethylaminoethyl column fractionation of serum, the bacteriostatic principle was eluted in proximity to blood group antibody; immunoglobulins A, G, and M appeared to be present in bacteriostatic fractions. It is suggested that S. aureus bacteriostasis by serum is due to natural antibody and that inhibitory reactions with pneumococci and coagulase are due to common antigens.
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PMID:Serum Bacteriostasis of Staphylococcus aureus. 1655 34


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