PubMed Health⌕ Search

Biomedical subjects

B Damerau

Publications and source records attributed to B Damerau.

At least 37 records · Page 2Linked to original sources
PubMed1985

Loss and recovery of sensitivity of guinea-pig isolated ileum to the spasmogenic action of the complement peptide C5adesArg.

Deactivation (tachyphylaxis) of the guinea-pig isolated ileum to the spasmogenic action of the complement peptide C5adesArg was analysed. It appeared to consist of 2 components: a fast one, characterized by rapid onset of deactivation and by recovery within 2-3 min (see Damerau et al., 1985b), and a slow component, characterized by progressively increasing loss of sensitivity (until complete deactivation after several minutes) and by recovery within about 80 min. Slow deactivation shows an exponential time course; it is dependent on concentration as well as contact time with C5adesArg and occurs under conditions (incubation in Ca2+-free medium or at 16 degrees C) in which the peptide has no spasmogenic effect. Recovery from slow deactivation follows an exponential time course at 34 degrees C but is blocked at 16 degrees C; on average it reaches about half of the initial sensitivity. The results indicate that the slow deactivation is mainly due to blockade of C5a receptors by the ligand and is independent of the spasmogenic effect of C5adesArg.

Animals↗
PubMed1985

Pharmacological characterization of the slow component of deactivation of guinea-pig isolated ileum to the spasmogenic action of C5adesArg.

The slow component of deactivation of guinea-pig isolated ileum to C5adesArg was studied to analyse the mechanism of loss and subsequent recovery of sensitivity. Neither cycloheximide (10(-3) M) nor colchicine (5 X 10(-5) M), vinblastine, lumicolchicine, or cytochalasin B (each 2 X 10(-5) M) affected significantly the spasmogenic effect of C5adesArg or the course of deactivation produced by repeated applications; chloroquine (2 X 10(-4) M) inhibited the spasmogenic effect unspecifically without interfering with deactivation. Recovery from slow deactivation was totally blocked by chloroquine and considerably diminished by colchicine and vinblastine, but was not affected by the other agents. It is proposed that recovery involves lysosomal processing of C5a receptors (occupied by the peptide) but does not require biosynthesis of new receptors.

Animals↗
PubMed1984

Cyclic nucleotides and their relationship to complement-component-C2 synthesis by human monocytes.

The time courses of changes in cyclic nucleotide levels in monocytes have been studied. Histamine and prostaglandin E2 (PGE2) produced a rapid rise in cyclic AMP (peak 15 min) levels, which returned to normal within 4h, whereas cholera toxin, NaF and phosphodiesterase inhibitors produced slow sustained rises lasting over 24h. With the exception of isobutylmethylxanthine (10 mumol X 1(-1), none of these reagents altered cyclic GMP levels. alpha 1-Adrenergic and nicotinic cholinergic receptor-ligand interactions and imidazole produced rapid and relatively short-lived falls in cyclic AMP, and rises in cyclic GMP. In contrast, prostaglandin synthetase inhibitors produced delayed but more sustained falls in cyclic AMP but no rises in cyclic GMP. Agents that increased cyclic AMP decreased complement-component-C2 production, and those that decreased cyclic AMP increased C2 production. Agents that increased cyclic GMP alone (ascorbate, nitroprusside and prostaglandin F2 alpha) did not affect C2 production. Antigen-antibody complexes that stimulate C2 synthesis produced falls in cyclic AMP and rises in cyclic GMP similar to those produced by adrenergic and cholinergic ligands. Serum-treated complexes and anaphylatoxins, which inhibited C2 production, were associated with changes in cyclic AMP similar to those produced by histamine and PGE2. These data suggest that there are two transmembrane signals involved in the regulation of C2 production by monocytes. The inhibitory signal is adenylyl cyclase activation. The stimulatory signal is not so obvious, but may be Ca2+ influx, since the time courses of changes in cyclic nucleotides produced by agents that stimulate C2 synthesis are identical, and alpha 1-adrenergic agonists cause the formation of Ca2+ channels.

Adenylyl Cyclases↗
PubMed1984

Influence of the anti-inflammatory serine esterase inhibitor gabexate mesilate (Foy) on aggregation, locomotion and adhesion of polymorphonuclear leukocytes.

The effects of the anti-inflammatory serine esterase inhibitor, gabexate mesilate (Foy) were studied, on locomotion, autoaggregation and adhesion of polymorphonuclear leukocytes stimulated with the complement peptide C5a-desArg. The drug inhibited aggregation as well as spontaneous and directed migration of human leukocytes at concentrations of about 10(-3) M. Adhesion of peritoneal guinea-pig leukocytes to autologous aortic strips was reduced at about 20 times lower drug concentrations. The inhibitory drug effects were highly time- and temperature-dependent. Experiments with the two major drug metabolites, pHB and epsilon GC, indicate that gabexate mesilate is not active by itself but rather by its hydrolytic aromatic metabolite pHB. The results further suggest that the inhibitory effects on leukocyte activities observed are not related to the anti-inflammatory effects of gabexate mesilate.

Animals↗
PubMed1984

Relationship between the transient cAMP increase, exocytosis from specific and azurophil granules and chemotaxis in neutrophil granulocytes.

The short transient increase of the intracellular cAMP concentration during the first minute following stimulation, exocytosis from specific and azurophil granules, random and directional locomotion were assessed following stimulation of human and equine neutrophils with f-Met-Leu-Phe, C5ades Arg, standard gamma globulin (SGG) and the ionophore A23187. Different leucocyte-activating agents elicited distinct patterns of responses. The results showed that: Chemotactic factors produced exocytosis of small amounts of vitamin B12-binding proteins but not beta-glucuronidase, in the absence of cytochalasin B. Chemotaxis, the appearance of the transient cAMP peak and exocytosis from specific granules in response to cytotaxins were strictly correlated in the absence of cytochalasin B but not if exocytosis was measured in the presence of cytochalasin B. Thus comparison of exocytosis measured in the presence of cytochalasin B with other functions may be misleading. The non-chemotactic agents tested (SGG, A23187) produced secretion but no cAMP peak within 1 minute after stimulation, indicating that the cAMP peak is no obligatory event for triggering exocytosis in general. The ionophore A23187 alone at a concentration of 10(-6) M produced exocytosis from specific granules only, increased motility of cells in suspension and a marked increment of neutrophil adhesion to glass and after a lag period a sustained increase in cAMP. SGG elicited release of both vitamin B12-binding proteins and beta-glucuronidase.

Calcimycin↗
PubMed1983

Comparison of adhesion to glass and aggregation of human leucocytes.

C5adesArg-induced leucocyte aggregation and neutrophil adhesion to glass were compared using the same cell separation technique and identical chemicals for preparing the media. Human serum albumin decreased adhesion to glass but had no effect on leucocyte aggregation induced by C5adesArg. In contrast, C5adesArg in Gey's solution with or without HSA, in serum or plasma stimulated leucocyte aggregation in a dose-dependent fashion. However, it did not alter neutrophil adhesion to glass. This indicates that leucocyte aggregation and neutrophil adherence to glass do not necessarily represent equivalent responses taking place on different substrata. Thus they may be mechanistically distinct.

Cell Adhesion↗
PubMed1983

Effects of the anti-inflammatory serine esterase inhibitor, FOY, on phospholipase A2 (EC 3.1.1.4) activity in rabbit polymorphonuclear leukocytes.

Phospholipase A2 activity of polymorphonuclear leukocytes (PMNLs) towards radioactively labelled phosphatidylethanolamine is inhibited by FOY (ethyl 4-(6-guanidinohexanoyloxy)-benzoate methanesulfonate) in concentrations above 10(-4)M. The inhibition is noncompetitive with respect to the substrate employed and depends on the pH. Impairment of PMNL phospholipase A2 activity could play a role in the anti-inflammatory effect of FOY: the release of fatty acids from membrane phospholipids is reduced and consequently also the biosynthesis of bioactive oxygenated arachidonate metabolites, among them inflammatory mediators.

Animals↗
PubMed1983

Anaphylatoxins inhibit C2 production.

Anaphylatoxins C5a and C3a and their des Arg derivatives inhibited C2 production by mononuclear phagocytes. C5a and C5adesArg which were approximately equipotent (IC50 = 10(-10) mol/l) were more effective than C3a (IC50 = 5 X 10(-8) mol/l) which was approximately 10-20-fold more potent than C3adesArg IC50 = 5 X 10(-6) mol/l). Inhibition of C2 production was only reversed slightly by the addition of either indomethacin or ETYA to the cultures. Intracellular levels of cAMP, were increased by anaphylatoxins. The level of cAMP showed a good inverse correlation with C2 levels in the culture supernatants. The data suggest that the reduction in C2 production produced by anaphylatoxins may be mediated by an increase in intracellular cAMP.

Anaphylatoxins↗
PubMed1982

Cytotaxin-induced cAMP peak in granulocytes: its relationship to crawling movements, chemokinesis and chemotaxis.

The relationship between the short transient intracellular increase in cAMP levels on the one hand and chemotaxis or crawling movements on the other hand was investigated using human and equine granulocytes. C5ades arg, f-met-leu-phe, human serum albumin and immunoglobulin were used as stimulating agents. There was no strict correlation between the induction of crawling movements or of chemokinesis in general and the generation of the cAMP peak. But there was so far a strict parallelism between the occurrence of the chemotactic response and the cAMP peak. However, the magnitude of the peak was not representative for the extent of directional locomotion. It seems possible that cAMP is an essential step in the transduction of the chemotactic response, but there is no proof for a causal relationship as yet.

Cell Movement↗
PubMed1982

Role of histamine in the spasmogenic effect of the complement peptides C3a and C5a-desArg (classical anaphylatoxin).

The role of endogenous histamine in the spasmogenic effect of the complement-derived peptides C3a and C5a-desArg (isolated from yeast-activated hog serum) was studied in strips of terminal guinea-pig ileum. The effect of C3a is apparently histamine-independent; it neither induces histamine release from the test organ nor is its spasmogenic action inhibited by the H1-antihistaminics pheniramine and triprolidine, used in concentrations effective against histamine. However, endogenous histamine may be involved in the spasmogenic effect of C5a-desArg; when applied repeatedly C5a-desArg induces histamine release during its first and second application. Furthermore, both H1-antihistaminics inhibited C5a-desArg-induced contractions considerably, though less efficiently than those of added histamine.

Anaphylatoxins↗
PubMed1981

Isolation and properties of a complement inhibitor from Naja haje venom, distinct from known anticomplementary factors in cobra venom.

A complement inhibitor (CI) has been isolated from cobra (Naja haje) venom which is distinct from the two known anticomplementary factors in cobra venom [1], in functional properties as well as structure. CI is a small (mol. wt 26,000, determined by sodium dodecyl sulphate gel electrophoresis), heat-labile glycoprotein; the amino acid composition is that of a globular protein. CI interferes at various steps of the complement sequence, including reactions of the classical and alternative pathway. No effect was observed on C4 fixation and on the assembly of the membrane attack complex from C6-9 (minor inhibiting effects, if present, have not been excluded). Initiation of the alternative pathway is inhibited by CI already at the stage of cleavage of factor B. CI binds to C4, C4b, C3 and C3b; since the major inhibitory action of CI is lost after washing of cell intermediates, complex formation and, as a consequence, steric hindrance may be responsible for the inhibiting effects of CI. CI also interferes with binding of C3b to C3b receptors on human erythrocytes. CI is non-toxic in mice when given intraperitoneally in doses of 5 microgram/g.

Amino Acids↗
PubMed1981

Diverging effects of chemotactic serum peptides and synthetic f-Met-Leu-Phe on neutrophil locomotion and adhesion.

The chemotactic serum peptide preparations CAT 1.6.1. and C5adesArg induced marked directional locomotion over a wide concentration range without significant effects on random locomotion and adhesion of human neutrophils in Gey's solution containing 2% HSA. In contrast, f-Met-Leu-Phe produced marked negative chemokinetic effects and its capacity to induce directional locomotion was more limited with respect to magnitude and concentration range. The negative chemokinetic effect of f-Met-Leu-Phe correlated closely with increased spreading and cell adhesion.

Cell Adhesion↗
PubMed1980

The filter technique for measuring leucocyte locomotion in vitro. Comparison of three modifications.

Three forms of filter technique for measuring random and directional locomotion of leucocytes have been compared: (1) the conventional one filter technique of Boyden (lower surface count method); (2) the two filter system with a lower cell-impermeable filter designed to count the cells at the underside of the upper filter as well as those on the lower filter (two filter count method); and (3) two filter systems counting only cells associated with the lower filter (lower filter count method). In some instances all three methods produce qualitatively similar results. In others totally different results are reproducibly obtained with identical cell preparations, media and attractants. Compared to the two filter count method, the lower surface count method and the lower filter count method are not sufficiently reliable. The discrepancies are partly due to errors in measuring the response. They are caused by variable cell adhesion to the filters resulting in a varying distribution of cells between the upper and lower filter and/or detachment of neutrophils from the upper filter. Some of the discrepancies are not due to errors in assessing the response, but to differences in gradient formation and drift of chemokinetic and chemotactic materials from one compartment to the other.

Cell Count↗
PubMed1980

Aggregation of leukocytes induced by the complement-derived peptides C3a and C5a and by three synthetic formyl-methionyl peptides.

The highly purified hog complement peptides C3a and C5a and three formylmethionyl peptides induced dose-dependent aggregation of human leukocytes. For the effect Ca2+ and Mg2+ ions were required; in their absence the peptides induced specific desensitization. Human serum albumin (1 and 2%) reduced aggregation, whereas equivalent or even higher concentrations of plasma or serum were not inhibitory. SH reagents, protease inhibitors (N-tosyl-L-lysyl-chloromethyl ketone, N-tosyl-L-phenylalanyl-chloromethyl ketone), and colchicine also inhibited aggregation, whereas cytochalasin B greatly enhanced it. Dose-response studies under comparable conditions showed that aggregation is induced in similar dose ranges as chemotaxis. This suggests that complement-derived peptides generated in vivo may contribute to leukocyte accumulation in two ways, first by causing adherence of leukocytes to endothelium (equivalent to aggregation) and then by promoting migration to the inflammatory site.

Calcium↗
PubMed1980

Biological activities of C5a and C5adesArg from hog serum.

The complement-derived peptides C5a and C5adesArg (highly purified from yeast-activated hog serum) were both active in the following biological assays: in aggregation of human leukocytes (potency ratio for C5a:C5adesArg 3:1), in aggregation of guinea pig platelets (10:1), in chemotaxis of peritoneal rabbit leukocytes (10:1), and in contraction of isolated guinea pig ileum (1.4:1). The fact that C5adesArg preparations have 30 and 40% of the activity of C5a in leukocyte aggregation and smooth muscle contraction but only 10% of C5a chemotactic activity, clearly indicates that aggregation and spasmogenic activity are inherent properties of C5adesArg. Evidence that C5adesArg owns all activities studied is further given by the following findings: chromatographic separation of mixtures of C5a and C5adesArg results in the appearance of two peaks of spasmogenic activity; treatment of C5adesArg with carbopeptidase B does neither lead to release of detectable arginine nor abrogate any of the biological effects; treatment of C5a with carboxypeptidase B reduces the activities quantitatively to those of C5adesArg, and liberates the theoretically expected amount of arginine.

Amino Acids↗
PubMed1980

Purification and partial amino acid sequence of classical anaphylatoxin from pig serum: identification with Des-Arg-C5a.

Complement was activated in hog serum and the biologically active peptide(s) derived from the fifth component of complement were purified. Treatment of the serum with yeast, without any precautions to inhibit serum arginine carboxypeptidase, allowed the recovery of only one active fraction, the classical anaphylatoxin; it was identified as des-Arg-C5a. When hog serum was activated with yeast in the presence of 1M epsilon-aminohexanoic acid (inhibitor of arginine carboxypeptidase), two active C5-derived fractions were obtained, C5a and des-Arg-C5a. A partial amino acid sequence of the classical anaphylatoxin (19 N-terminal and 12 C-terminal amino acids) has been elaborated. With one exception it is identical with hog C5a as far as that structure is known (12 N-, 3 C-terminal amino acids). The only difference is the C-terminal region: arginine, present in C5a, is absent from des-Arg-C5a which ends with ... Asn-Ile-Gln-Leu-Gly-OH. The finding that des-Arg-C5a, virtually free of any significant contamination with C5a, has considerable spasmogenic activity demonstrates that it is the classical anaphylatoxin, and that for spasmogenic activity arginine as the C-terminal amino acid is not absolutely essential.

Amino Acid Sequence↗
PubMed1978

Chemotactic effects of the complement-derived peptides C3a, C3ai and C5a (classical anaphylatoxin) on rabbit and guinea-pig polymorphonuclear leukocytes.

The complement-derived peptides C3a, C3ai and C5a (= classical anaphylatoxin) were purified from hog serum and examined for chemotactic activity on rabbit and guinea-pig polymorphonuclear leukocytes (PMN) with the Boyden chamber technique (with filters of 3,0 micrometer pore size). When media containing albumin or serum were used all peptides induced chemotaxis of both cell species. Only C3a showed a pronounced species dependence in that it was much more active on rabbit than on guinea-pig PMN. No gross differences were found between the influence of 0.5% BSA and 10% heated (56 degree, 30 min) homologous serum added to the medium. In the absence of protein chemotaxis did not occur.

Anaphylatoxins↗