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At least 325 records · Page 18Linked to original sources
PubMed1979

Effect of leukocyte hydrolases on bacteria. XIII. Role played by leukocyte extracts, lysolecithin, phospholipase a2, lysozyme, cationic proteins, and detergents in the solubilization of lipids from Staphylococcus aureus and group A streptococci: relation to bactericidal and bacteriolytic reactions in inflammatory sites.

The bactericidal and bacteriolytic effects of lysolecithin (LL) and egg-white lysozyme (LYZ) on Staph. aureus and group A streptococci and the solubilization of phospholipids from the bacterial membranes by these agents was studied. Low concentrations of lysolecithin (1--10 microgrames/ml) are highly bactericidal for Steph. aureus and group A streptococci, but induce neither bacteriolysis nor solubilization of a substantial amount of membrane phospholipids. On the other hand, while LL at greater than 50 micrograms/ml causes substantial lipid release, a combination of LL and LYZ is absolutely needed to solubilize lipids from streptococci. This combination is, however, not bacteriolytic for this microrganism. The solubilization of lipids from staphylococci by LL is much faster than that induced in streptococci by LL + LYZ. The solubilization of the bulk of membrane lipids from staphylococci can also be achieved by Triton X-100 and by sodium lauryl sulfate and from group A streptococci by Triton X-100 plus LYZ. A variety of other detergents (e.g., Cetavlon, sodium taurocholate, cetyl pyrdinium chloride) have no lipid-releasing properties even in the presence of LYZ. The release of lipids by LYZ (in the presence of LL) from group A streptococci is related to its enzymatic activity, on a still unknown substrate, but not to its cationic nature as this muramidase cannot be replaced by a variety of cation substances (histone, polylysin, leukocyte cationic proteins, polymyxin B, and spermidine). The release of lipids from staphylococci by LL is not inhibited by a variety of anionic and cationic polyelectrocytes (heparin, liquoid, chondroitin sulfate, DNA histone, and polylysine) which markedly inhibit the release of lipids from group A streptococci by LL and LYZ. Streptococci that had been cultivated in the presence of subinhibitory concentrations of penicillin G lose their membrane phospholipids to a larger extent and by much smaller concentrations of LL and LYZ, as compared to controls, suggesting that the interference with the synthesis of the peptidoglycan increases the accessibility of the cell membrane to the lipid-releasing agents. The mechanism by which LL collaborates with LYZ in lipid release is still not known. The possible role of bacterial lipids and lyso compounds in the control of bacterial survival in inflammatory sites is briefly discussed.

Cell Membrane↗
PubMed1991

Comparison of group I and II soluble phospholipases A2 activities on phagocytic functions of human polymorphonuclear and mononuclear phagocytes.

Soluble phospholipase A2 (PLA2) purified from rheumatoid synovial fluid (group II) and repurified Naja naja venom PLA2 (group I) were compared for their influence on phagocytic activity of human polymorphonuclear (PMN) and mononuclear (MO) phagocytes. Group II PLA2 reduced chemotaxis, adhesiveness, and intracellular bactericidal activity (ICBA) and induced release of muramidase from PMNs. Group I PLA2 suppressed chemotaxis, and enhanced ICBA but had no influence on other phagocytic functions. Group II PLA2 purified from synovial fluid or from placenta caused marked spontaneous superoxide generation followed by inhibition of phagocytosis-induced burst of energy. Group I Naja naja and porcine pancreatic PLA2 had no effect on superoxide generation. Group II but not group I PLA2 reduced markedly ICBA of monocytes. It may be concluded that human group II soluble PLA2, in concentrations comparable to those present in inflamed joints or in sera of patients with active arthritis or septic shock, causes spontaneous formation of the oxygen radical superoxide and release of lysosomal enzymes, and suppresses conventional phagocytic activities of PMNs and monocytes. Marked differences between group I and group II PLA2s may mean that these enzymes exert different influences on cell membrane.

Arthritis, Rheumatoid↗
PubMed1977

[Serum lysozyme concentrations in patients with morbus Crohn before and after bowel resection (author's transl)].

Serum lysozyme (muramidase) concentrations were determined in five patients with Morbus Crohn before and after resection of inflammated bowel areas. The serum lysozyme activity which was elevated before surgical treatment in all patients fell to normal values after bowel resection within a few hours. Our findings suggest, that the elevated serum lysozyme reflects an increased lysozyme production in the inflammated bowel tissue.

Colitis, Ulcerative↗
PubMed1975

Assessment of the value of prednisone test in differential diagnosis of neutropenic state.

The prednisone test revealed normal bone marrow reserve of neutrophils (BMR) in subjects with innocent neutropenias e.g. neutropenias not associated with any other disturbances in haemopoiesis or with increased incidence of infections, assumed to be an individual anomaly of the subject. On the other hand, diminution or absence of MBR in chronic hypoplastic neutropenias, transient post-chemotherapeutic neutropenias and neutropenias with increased destruction of neutrophils were observed. The magnitude of that diminution was not dependent of the cause of neutropenia. It is suggested, that the prednisone test (and probably tests with other BMR mobilizing agents) may serve as screening tests for exclusion (or confirmation) of relative granulopoietic insufficiency as the cause of neutropenia. Only after confirmation of reduced BMR another explanations of neutropenia should be sought using other method as muramidase level, adrenaline test or granulocyte kinetics with DF32P, 3HDFP, or 51Cr.

Adolescent↗
PubMed1975

[Some properties of carrier strains of Listeria monocytogenes (author's transl)].

About 60 characteristics have been investigated in 7 hemolyzing and 12 nonhemolyzing strains of L. monocytogenes. From these investigations resulted inter alia that the organism grows well under strictly anaerobic conditions, esculin is split at 45 degrees C,NH3 is produced from peptone, but not from arginin, and H2S can be traced by sufficiently sensitive methods. All strains possess a lipase, muramidase, and deoxyribonuclease, the hemolytic ones only also a lecithinase. Besides, the hemolytic strains only dispose of experimental virulence and of a CAMP factor-like agent. The experimental animal of choice seems to be the conjunctivally infected guinea pig in which a generalized infection develops.

Ammonia↗
PubMed2002

Modification of the peptidoglycan of Escherichia coli in the viable but nonculturable state.

The aim of this study was to analyse the chemical composition of peptidoglycan and the state of some of the enzymes involved in its metabolism in Escherichia coli KN126 in the viable but nonculturable (VBNC) state which is a survival strategy adopted by bacteria (including those of medical interest) when exposed to environmental stresses. When entering the VBNC state, E. coli cells miniaturised and became coccus-shaped. Analysis of peptidoglycan chemical composition, by separation in HPLC of muropeptides released by muramidase digestion of purified peptidoglycan, indicated a high degree of cross-linking, a threefold increase in unusual DAP-DAP cross-linking, an increase in muropeptides bearing covalently bound lipoprotein, and a shortening of the average length of glycan strands in comparison with dividing cells. Analysis of penicillin-binding proteins (PBPs), enzymes involved in the terminal stage of peptidoglycan assembly showed the disappearance of high-molecular-weight PBPs 1A, 1B, 2, and 3 in VBNC cells. Finally, VBNC cells displayed an autolytic capability which was far higher than that of exponentially growing cells. It is suggested that part of these alterations of peptidoglycan may be connected with the VBNC state.

Antigens, Bacterial↗
PubMed1997

Lysozyme expression in the rat parotid gland: light and electron microscopic immunogold studies.

Lysozyme (muramidase) is capable of direct bacteriolytic action by hydrolyzing glycosidic bonds in bacterial cell walls. Although it is broadly distributed in vertebrate tissues and secretions, the cellular and subcellular localizations of the enzyme are still not well known. The present study examines the distribution of lysozyme expression in the various cell types of LR gold-embedded rat parotid gland, applying a postembedding immunogold-silver staining technique for light microscopy. Simultaneously, a postembedding immunogold method for electron microscopy was used to determine the cellular compartments engaged in the biosynthesis and exocytosis of lysozyme. Silver-amplified immunogold staining for lysozyme demonstrated identical localization in both paraffin and semithin LR-gold sections: in the supranuclear parts of acinar and intercalated duct cells. Staining intensity varied even between adjacent cells. In the electron microscope, immunogold labeling was detected over the cell compartments associated with protein synthesis and exocytosis in acinar and intercalated duct cells. Lysozyme antigenic sites were visible over endoplasmic reticulum and throughout the Golgi apparatus, being intense over the trans-Golgi network, but even stronger in the condensing vacuoles and most prominent over secretory granules in both cell types. The findings provide the first immunocytochemical evidence of the synthesis and secretion of lysozyme in parotid acinar and intercalated duct cells.

Animals↗
PubMed1986

Determination of lysozyme activity at low levels with emphasis on the milk enzyme.

A method is described for the determination of lysozyme (muramidase) activity, whereby sensitivity is maximized by incubation of the reaction mixture (sample, buffer, and substrate (Micrococcus luteus] over an extended period. This approach is made feasible by exploiting our observation that the lytic reaction follows simple kinetic order during this time (e.g., 700 min for bovine lysozyme and 960 min for the eggwhite enzyme at low concentrations). After this period, the reaction rates diminish, indicating biphasic behavior, and eventually become negligible. The kinetic order may vary with both the type of lysozyme and the buffer system used. The limit of detection for bovine milk lysozyme is 100 pg/ml reaction mixture, equivalent to 6 ng/ml milk, for a 50-microliters sample (with reference to hen eggwhite lysozyme). With these limits, the method has proven valuable in our comparative studies, particularly for low levels of activity in bovine milk, but also in secretions and tissue extracts from various other eutherian, metatherian, and prototherian mammals. The method may also be applied to investigation of structure and function in modified forms of the enzyme.

Animals↗
PubMed1988

Separation and quantification of muropeptides with high-performance liquid chromatography.

About 80 different muropeptides, the subunits which comprise the polymer murein of Escherichia coli, were resolved by high-performance liquid chromatography. The muropeptides were released from isolated murein by complete digestion with muramidase from Chalaropsis spec. The separation method is based on reversed phase chromatography of the sodium borohydride-reduced compounds using ODS (C18) columns and a linear gradient elution with sodium phosphate buffer and methanol as organic modifier. The effect of temperature, pH, ionic strength, and the steepness of the gradient and of different support materials on the separation of the muropeptides was investigated. The new method represents a major improvement over previous methods with respect to resolution, sensitivity, and speed. Analytical as well as preparative separations can be realized. Quantitative analysis of murein composition is achieved by a linear gradient from 50 mM sodium phosphate, pH 4.31, to 75 mM sodium phosphate, pH 4.95, containing 15% methanol for 135 min on a 250 X 4.6 mm 3-micron Hypersil ODS column at 55 degrees C using a flow rate of 0.5 ml/min. With uv detection at 205 nm about 20 micrograms of murein per analysis is sufficient. The detection limit per compound is about 5 ng. A method for the evaluation of the analytical data allowing a convenient comparison of different muropeptide pattern is described.

Cell Wall↗
PubMed1990

Isolation and separation of the glycan strands from murein of Escherichia coli by reversed-phase high-performance liquid chromatography.

The length distribution of the glycan strands in the murein (peptidoglycan) sacculus of Escherichia coli has been analyzed after solubilization of the murein by complete digestion with human serum amidase. The glycan strands released were separated according to length by reversed-phase HPLC on wide-pore Nucleosil 300 C18 material at 50 degrees C, employing a convex gradient from 5 to 11% acetonitrile. The length of the fractionated glycan strands, which carry a nonreducing 1,6-anhydromuramic acid as a natural end group, was calculated from the ratio of total to nonreducing terminal muramic acid residues. This was possible after complete hydrolysis of the isolated glycan strands by muramidase followed by separation of the released nonreducing and reducing di- and tetrasaccharides by reversed-phase HPLC on Hypersil C18. The method established allows the separation of the glycan strands of murein, a poly-GlcNAc(beta 1-4)MurNAc-polysaccharide, up to a degree of polymerization of approximately 60. The predominant lengths of the glycan strands were 5 to 10 GlcNAc(beta 1-4)MurNAc disaccharide units.

Acetylglucosamine↗
PubMed1982

Lysozyme binding by a polyglycerol phosphate polymer of the oral bacterium Streptococcus mutans BHT.

The antibacterial properties of lysozyme for Streptococcus mutans BHT may be a function of its binding to cell components other than to peptidoglycan. Inhibitors of muramidase activity, including histamine and N-acetyl-D-glucosamine, only partially blocked the bacteriostatic effects on this strain. Greater than 20 mM histamine alone inhibited growth suggesting a bacteriostatic potential. An autoclaved saline extract was then prepared from stationary phase cultures in a chemically-defined medium. As little as 31.25 micrograms of the extract significantly blocked the effect of 50 micrograms lysozyme and complete enzyme inhibition was achieved with 62.5 micrograms. The extract was fractionated and location of potential binding components determined by a precipitin method consisting of diffusing the samples into 1.2 per cent agarose containing lysozyme. Binding components eluted in the first peak of a Sephacryl S-300 column, bound to DEAE-cellulose, but desorbed with gradient elution (0.1-1.0 M tris-HCl buffer, pH 8.0). The eluted material was then applied to an affinity column containing purified lysozyme coupled to epoxy-activated Sepharose 6B. Non-absorbed anionic material precipitated only with protamine. Lysozyme-binding fractions eluted in a sharp peak with 1.0 M tris-HCl buffer (pH 8.0), did not bind wheat-germ agglutinin, contained less than 50 micrograms protein, 95 micrograms sugar, 66.7 micrograms phosphorus, less than 0.25 mequiv lipid and no detectable nucleic acids. The peak material reacted with antiserum directed against polyglycerol phosphate, indicating that it contained acylated or, possibly, deacylated lipoteichoic acid. The findings suggest that the antibacterial properties of lysozyme for Strep. mutans BHT may, in part, be modified (or possibly regulated) by binding to molecules such as lipoteichoic acid.

Glycerophosphates↗
PubMed1983

Studies on gentamicin-induced labilization of rat kidney lysosomes in vitro. Possible protection by selenium.

The labilizing effect of gentamicin, an aminoglycoside antibiotic, on isolated rat kidney lysosomes was investigated. The light-scattering behavior of lysosomal suspensions and the release of lysosomal acid hydrolase enzymes (acid phosphatase, beta-glucuronidase and muramidase) from incubated lysosomal suspensions, in the presence of gentamicin, were used as indices of lysosomal membrane labilization. Gentamicin was found to cause a decrease in light absorbance and a release of lysosomal acid hydrolases, which indicate lysosomal membrane swelling. In the presence of selenium, in the form of potassium selenate, the decrease in light absorbance of lysosomal suspensions and the release of lysosomal acid hydrolases from isolated lysosome particles were reduced markedly. This suggests that selenium protects against gentamicin-induced lysosomal membrane labilization. The possible mechanisms of protection by selenium are discussed.

Acid Phosphatase↗
PubMed1984

Lysozyme levels in rabbit lung after inhalation of nickel, cadmium, cobalt, and copper chlorides.

Groups of rabbits were exposed to chlorides of nickel, cadmium, copper, and cobalt at concentrations ranging from 0.2 to 0.6 mg/m3 (as metal) for 4-6 weeks (5 days/week, 6 hr/day). Activity of lysozyme (muramidase) in lavage fluid, in alveolar macrophages, and in culture medium from macrophages incubated at 37 degrees C for 1 and 20 hr was estimated using the lyso-plate technique, agar plates with heat-killed Micrococcus lysodeikticus. In the nickel-exposed rabbits lysozyme activity in the mucous membrane from the left main bronchus was also estimated. Following nickel exposure the lysozyme level was significantly decreased in lavage fluid, macrophages, and in culture medium from incubated macrophages but remained unchanged in the mucous membrane. After exposure to cadmium, copper, and cobalt, lysozyme levels increased or were unchanged.

Animals↗
PubMed1989

Pathology, histochemistry and immunocytochemistry of lesions in acute multiple sclerosis.

Twenty cases of acute or early multiple sclerosis have been examined using staining, histochemical or immunocytochemical methods. They had died within 6 months after initial clinical onset (12) or commencement of an "anatomically-remote" acute relapse (8). Plaques in these acute cases showed the following characteristics: lymphocytic perivascular infiltration, plaque hypercellularity, plaque macrophage infiltration and intra-macrophage myelin debris. In most cases of clinical duration of less than 12 weeks, some macrophages showed characteristic formaldehyde-resistant markers for haematogenous macrophages (muramidase, anti-alpha 11-antitrypsin, MAC and HAM56) but, with the exception of the last, these markers subsequently declined indicating a haematogenous origin for macrophages in the early lesion. Lymphocytes were prominent in perivascular (perivenous) regions but, except in one case, were only scanty in or at the demyelinating edge of plaques. Oligodendroglial hyperplasia, indicative of remyelinating activity, was seen at the edge of plaques in one quarter of these acute cases (7 times the rate seen in chronic lesions). Astrocytic activation was not apparent in the earliest stages but was usually seen from about 6 weeks onwards. The conclusion from these observations is that the prime inflammatory process is around blood vessels with usually only scanty initial inflammatory activity in the parenchyma of the brain. Macrophages emigrating from blood vessels digest myelin either as a response to inflammatory damage to the myelin or as a response to activation signals produced in either the perivascular region or plaque.

Adolescent↗
PubMed1985

Immunohistochemical identification of alpha-1-antitrypsin, alpha-1-antichymotrypsin, and lysozyme in focal hyperplastic gingivitis.

Tissues from twenty-four patients with focal hyperplastic gingival lesions containing calcification were stained for lysozyme (muramidase), alpha-1-antitrypsin, and alpha-1-antichymotrypsin. In eighteen of the twenty-four cases the tissues stained positively for lysozyme, and in all instances the tissues stained positively for alpha-1-antitrypsin and alpha-1-antichymotrypsin. These data suggest that the fibrous components of these lesions are derived from tissue histiocytes.

Calcinosis↗
PubMed1994

Serotypes and putative virulence markers of Streptococcus suis isolates from cats and dogs.

Thirteen isolates of Streptococcus suis from cats and dogs were characterised. Formamide extracts of 10 of the 13 cultures reacted with group D specific antiserum, and serotyping of the cultures with specific antisera against capsular types 1 to 28 revealed the serotypes 9, 20, 1/2, 22, 26 and 4; the remaining cultures were untypable. In addition one of the cultures reacted with monoclonal antibodies against muramidase-released protein and in parallel with monoclonal antibodies against the extracellular factor (EF) of S suis. The latter reacted with proteins with a molecular weight of more than 150,000 indicating that the strain exhibited EF-related proteins. One of the 13 cultures haemagglutinated erythrocytes from human beings and various animal species and adhered in large numbers to HeLa cells.

Animals↗
PubMed1996

Expression and purification of a recombinant metal-binding T4 lysozyme fusion protein.

Periplasmic expression of recombinant proteins presents many potential benefits that may aid recovery of the protein product. Muramidases are the preferred agents in effecting selective release of recombinant proteins from the periplasm of E. coli and other Gram negative bacteria. Unfortunately cost restricts the use of pure lytic enzymes at large-scale and their removal as process contaminants adds to later purification demands. We constructed a reusable version of bacteriophage T4 lysozyme, by fusing a His-Gln-(His)3 peptide sequence to the C-terminus of a cysteine-free pseudo wild type bacteriophage T4 lysozyme. The peptide tail allowed rapid and high-level recovery on IDA Sepharose columns charged with Zn2+, Ni2+ and Cu2+ ions. The binding to metal-charged supports was specifically mediated by the histidine-rich tail as no binding was observed for the original cysteine-free pseudo wild type lysozyme. The strength of retention of polyhistidine recombinant T4 lysozyme on charged supports followed the expected Cu > Ni > Zn pattern, but there were few differences in the levels of purity and recovery of the modified enzyme, from columns charged with the different metal ions.

Cysteine↗
PubMed1985

The isolation and characterization of lysozyme from human foetal membranes: a comparison with the enzyme from other sources.

Lysozyme (muramidase) was isolated from an acidic extract of human foetal membranes by adsorption and elution from octadecyl silica. It was further purified by gel-filtration and ion-exchange. The final product was homogeneous by high performance liquid chromatography (h.p.l.c.) and electrophoresis. It was indistinguishable from human milk lysozyme by all criteria investigated, including amino acid composition, electrophoretic mobility, retention time on h.p.l.c. and sequence of the first nine residues. Human uterine decidual tissue was shown to contain a similar concentration of lysozyme to foetal membranes. The enzyme was also present at lower concentrations in amnion, placenta and amniotic fluid.

Amino Acids↗